SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
Sep. 30, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements have been prepared in accordance with Generally Accepted Accounting Principles in the United States of America (“U.S. GAAP”). We meet the definition of an investment company and follow the accounting and reporting guidance in the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 946 – Financial Services – Investment Companies (“ASC 946”). Under rules and regulations applicable to investment companies, we are generally precluded from consolidating any entity other than another investment company, subject to certain exceptions. One of the exceptions to this general principle occurs if the investment company has an investment in an operating company that provides services to the investment company. Accordingly, the consolidated financial statements include the Taxable Subsidiary. The consolidated financial statements are presented in conformity with U.S. GAAP for interim financial information and pursuant to the requirements for reporting on Form 10-Q and Article 10 of Regulation S-X. Accordingly, certain disclosures accompanying annual consolidated financial statements prepared in accordance with U.S. GAAP are omitted. In the opinion of our management, the unaudited consolidated financial results included herein contain all adjustments, consisting solely of normal recurring accruals, considered necessary for the fair presentation of consolidated financial statements for the interim periods included herein. The results of operations for the three and six months ended September 30, 2022 are not necessarily indicative of the operating results to be expected for the full fiscal year. Also, the unaudited consolidated financial statements and notes should be read in conjunction with the audited consolidated financial statements and notes thereto for the fiscal years ended March 31, 2022 and 2021. Consolidated financial statements prepared on a U.S. GAAP basis require management to make estimates and assumptions that affect the amounts and disclosures reported in the consolidated financial statements and accompanying notes. Such estimates and assumptions could change in the future as more information becomes known, which could impact the amounts reported and disclosed herein.
Investments	Portfolio Investment Classification We classify our investments in accordance with the requirements of the 1940 Act. Under the 1940 Act, “Control Investments” are generally defined as investments in which we own more than 25% of the voting securities; “Affiliate Investments” are generally defined as investments in which we own between 5% and 25% of the voting securities, and the investments are not classified as “Control Investments”; and “Non-Control/Non-Affiliate Investments” are generally defined as investments that are neither “Control Investments” nor “Affiliate Investments.” Under the 1940 Act, a BDC must meet certain requirements, including investing at least 70% of its total assets in qualifying assets. As of September 30, 2022, the Company has 87.1% of its assets in qualifying assets. The principal categories of qualifying assets relevant to our business are: (1)Securities purchased in transactions not involving any public offering from the issuer of such securities, which issuer (subject to certain limited exceptions) is an "eligible portfolio company," or from any person who is, or has been during the preceding 13 months, an affiliated person of an eligible portfolio company, or from any other person, subject to such rules as may be prescribed by the Securities and Exchange Commission ("SEC"). (2)Securities of any eligible portfolio company that we control. (3)Securities purchased in a private transaction from a U.S. issuer that is not an investment company or from an affiliated person of the issuer, or in transactions incident thereto, if the issuer is in bankruptcy and subject to reorganization or if the issuer, immediately prior to the purchase of its securities was unable to meet its obligations as they came due without material assistance other than conventional lending or financing arrangements. (4)Securities of an eligible portfolio company purchased from any person in a private transaction if there is no readily available market for such securities and we already own 60% of the outstanding equity of the eligible portfolio company. (5)Securities received in exchange for or distributed on or with respect to securities described in (1) through (4) above, or pursuant to the exercise of warrants or rights relating to such securities. (6)Cash, cash equivalents, U.S. government securities or high-quality debt securities maturing in one year or less from the time of investment. Additionally, in order to qualify for RIC tax treatment for U.S. federal income tax purposes, we must, among other things meet the following requirements: (1) Continue to maintain our election as a BDC under the 1940 Act at all times during each taxable year. (2) Derive in each taxable year at least 90% of our gross income from dividends, interest, payments with respect to certain securities, loans, gains from the sale of stock or other securities, net income from certain "qualified publicly traded partnerships," or other income derived with respect to our business of investing in such stock or securities. (3) Diversify our holdings in accordance with two Diversification Requirements: (a) Diversify our holdings such that at the end of each quarter of the taxable year at least 50% of the value of our assets consists of cash, cash equivalents, U.S. Government securities, securities of other RICs, and such other securities if such other securities of any one issuer do not represent more than 5% of the value of our assets or more than 10% of the outstanding voting securities of the issuer; and (b) Diversify our holdings such that no more than 25% of the value of our assets is invested in the securities, other than U.S. government securities or securities of other RICs, (i) of one issuer, (ii) of two or more issuers that are controlled, as determined under applicable Code rules, by us and that are engaged in the same or similar or related trades or businesses or (iii) of certain "qualified publicly traded partnerships" (collectively, the "Diversification Requirements"). The two Diversification Requirements must be satisfied quarterly. If a RIC satisfies the Diversification Requirements for one quarter, and then, due solely to fluctuations in market value, fails to meet one of the Diversification Requirements in the next quarter, it retains RIC tax treatment. A RIC that fails to meet the Diversification Requirements as a result of a nonqualified acquisition may be subject to excess taxes unless the nonqualified acquisition is disposed of and the Diversification Requirements are satisfied within 30 days of the close of the quarter in which the Diversification Requirements are failed. Investments Investments are stated at fair value and are reviewed and approved by our Board of Directors as described in the Notes to the Consolidated Schedule of Investments and Notes 3 and 4 below. Investments are recorded on a trade date basis. Net Realized Gains or Losses and Net Unrealized Appreciation or Depreciation Realized gains or losses are measured by the difference between the net proceeds from the sale or redemption of an investment or a financial instrument and the cost basis of the investment or financial instrument, without regard to unrealized appreciation or depreciation previously recognized, and includes investments written-off during the period net of recoveries and realized gains or losses from in-kind redemptions. Net unrealized appreciation or depreciation reflects the net change in the fair value of the investment portfolio and financial instruments and the reclassification of any prior period unrealized appreciation or depreciation on exited investments and financial instruments to realized gains or losses. Investment Valuation Process The valuation process is led by the finance department in conjunction with the investment team. The process includes a quarterly review of each investment by our executive officers and investment team. Valuations of each portfolio security are prepared quarterly by the finance department using updated financial and other operational information collected by the investment team. Each investment valuation is then subject to review by the executive officers and investment team. In conjunction with the internal valuation process, we have also engaged multiple independent consulting firms specializing in financial due diligence, valuation, and business advisory services to provide third-party valuation reviews of certain investments. The third-party valuation firms provide a range of values for selected investments, which is presented to CSWC’s executive officers and then subsequently to the Board of Directors. CSWC also uses a standard internal investment rating system in connection with its investment oversight, portfolio management, and investment valuation procedures for its debt portfolio. This system takes into account both quantitative and qualitative factors of the portfolio company and the investments held therein. There is no single standard for determining fair value in good faith, as fair value depends upon the specific circumstances of each individual investment. While management believes our valuation methodologies are appropriate and consistent with market participants, the recorded fair values of our investments may differ significantly from fair values that would have been used had an active market for the securities existed. In addition, changes in the market environment and other events that may occur over the life of the investments may cause the gains or losses ultimately realized on these investments to be different than the valuations currently assigned. The Board of Directors has the ultimate responsibility for reviewing and determining, in good faith, the fair value of CSWC’s investments in accordance with the 1940 Act.
Fair Value Measurements	Fair Value Measurements We account for substantially all of our financial instruments at fair value in accordance with ASC Topic 820 – Fair Value Measurements and Disclosures (“ASC 820”). ASC 820 defines fair value, establishes a framework used to measure fair value and requires disclosures for fair value measurements, including the categorization of financial instruments into a three-level hierarchy based on the transparency of valuation inputs. ASC 820 requires disclosure of the fair value of financial instruments for which it is practical to estimate such value. We believe that the carrying amounts of our financial instruments such as cash, receivables and payables approximate the fair value of these items due to the short maturity of these instruments. This is considered a Level 1 valuation technique. The carrying value of our credit facility approximates fair value (Level 3 input). See Note 4 below for further discussion regarding the fair value measurements and hierarchy.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents, which consist of cash and highly liquid investments with an original maturity of three months or less at the date of purchase, are carried at cost, which approximates fair value. Cash may be held in a money market fund from time to time, which is a Level 1 security. Cash and cash equivalents includes deposits at financial institutions. We deposit our cash balances in financial institutions and, at times, such balances may be in excess of the Federal Deposit Insurance Corporation (“FDIC”) insurance limits. At September 30, 2022 and March 31, 2022, cash balances totaling $29.0 million and $10.2 million, respectively, exceeded FDIC insurance limits, subjecting us to risk related to the uninsured balance. All of our cash deposits are held at large established high credit quality financial institutions and management believes that the risk of loss associated with any uninsured balances is remote.
Segment Information	Segment Information We operate and manage our business in a singular segment. As an investment company, we invest in portfolio companies in various industries and geographic areas as discussed in Note 3.
Consolidation	Consolidation As permitted under Regulation S-X and ASC 946, we generally do not consolidate our investment in a portfolio company other than an investment company subsidiary or a controlled operating company whose business consists of providing services to CSWC. Accordingly, we consolidate the results of CSWC’s wholly-owned Taxable Subsidiary and SBIC I. All intercompany balances have been eliminated upon consolidation.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. We have identified investment valuation and revenue recognition as our most critical accounting estimates.
Interest Income	Interest and Dividend Income Interest and dividend income is recorded on an accrual basis to the extent amounts are expected to be collected. Dividend income is recognized on the date dividends are declared by the portfolio company or at the point an obligation exists for the portfolio company to make a distribution. Discounts/premiums received to par on loans purchased are capitalized and accreted or amortized into income over the life of the loan using the effective interest method. In accordance with our valuation policy, accrued interest and dividend income is evaluated quarterly for collectability. When we do not expect the debtor to be able to service all of its debt or other obligations, we will generally establish a reserve against interest income receivable, thereby placing the loan or debt security on non-accrual status, and cease to recognize interest income on that loan or debt security until the borrower has demonstrated the ability and intent to pay contractual amounts due. If a loan or debt security’s status significantly improves regarding its ability to service debt or other obligations, it will be restored to accrual basis. As of September 30, 2022, investments on non-accrual status represented approximately 0.9% of our total investment portfolio's fair value and approximately 2.3% of its cost. As of March 31, 2022, investments on non-accrual status represented approximately 1.5% of our total investment portfolio's fair value and approximately 2.6% of its cost. To maintain RIC tax treatment, non-cash sources of income such as accretion of interest income may need to be paid out to shareholders in the form of distributions, even though CSWC may not have collected the interest income. For the three and six months ended September 30, 2022, approximately 3.6% and 3.7%, respectively, of CSWC's total investment income was attributable to non-cash interest income for the accretion of discounts associated with debt investments, net of any premium reduction. For the three and six months ended September 30, 2021, approximately 3.6% and 3.7%, respectively, of CSWC's total investment income was attributable to non-cash interest income for the accretion of discounts associated with debt investments, net of any premium reduction. Payment-in-Kind Interest The Company currently holds, and expects to hold in the future, some investments in its portfolio that contain payment-in-kind (“PIK”) interest provisions. The PIK interest, computed at the contractual rate specified in each loan agreement, is added to the principal balance of the loan, rather than being paid to the Company in cash, and is recorded as interest income. Thus, the actual collection of PIK interest may be deferred until the time of debt principal repayment. PIK interest, which is a non-cash source of income, is included in the Company’s taxable income and therefore affects the amount the Company is required to distribute to shareholders to maintain its qualification as a RIC for U.S. federal income tax purposes, even though the Company has not yet collected the cash. Generally, when current cash interest and/or principal payments on a loan become past due, or if the Company otherwise does not expect the borrower to be able to service its debt and other obligations, the Company will place the investment on non-accrual status and will generally cease recognizing PIK interest income on that loan for financial reporting purposes until all principal and interest have been brought current through payment or due to a restructuring such that the interest income is deemed to be collectible. The Company writes off any accrued and uncollected PIK interest when it is determined that the PIK interest is no longer collectible.
Dividends Income	Interest and Dividend Income Interest and dividend income is recorded on an accrual basis to the extent amounts are expected to be collected. Dividend income is recognized on the date dividends are declared by the portfolio company or at the point an obligation exists for the portfolio company to make a distribution. Discounts/premiums received to par on loans purchased are capitalized and accreted or amortized into income over the life of the loan using the effective interest method. In accordance with our valuation policy, accrued interest and dividend income is evaluated quarterly for collectability. When we do not expect the debtor to be able to service all of its debt or other obligations, we will generally establish a reserve against interest income receivable, thereby placing the loan or debt security on non-accrual status, and cease to recognize interest income on that loan or debt security until the borrower has demonstrated the ability and intent to pay contractual amounts due. If a loan or debt security’s status significantly improves regarding its ability to service debt or other obligations, it will be restored to accrual basis. As of September 30, 2022, investments on non-accrual status represented approximately 0.9% of our total investment portfolio's fair value and approximately 2.3% of its cost. As of March 31, 2022, investments on non-accrual status represented approximately 1.5% of our total investment portfolio's fair value and approximately 2.6% of its cost. To maintain RIC tax treatment, non-cash sources of income such as accretion of interest income may need to be paid out to shareholders in the form of distributions, even though CSWC may not have collected the interest income. For the three and six months ended September 30, 2022, approximately 3.6% and 3.7%, respectively, of CSWC's total investment income was attributable to non-cash interest income for the accretion of discounts associated with debt investments, net of any premium reduction. For the three and six months ended September 30, 2021, approximately 3.6% and 3.7%, respectively, of CSWC's total investment income was attributable to non-cash interest income for the accretion of discounts associated with debt investments, net of any premium reduction.
Fee Income	Fee Income Fee income, generally collected in advance, includes fees for administration and valuation services rendered by the Company. These fees are typically charged annually and are amortized into income over the year. The Company recognizes nonrecurring fees, including prepayment penalties, waiver fees and amendment fees, as fee income when earned. In addition, the Company may also be entitled to an exit fee that is amortized into income over the life of the loan. Loan exit fees to be paid at the termination of the loan are accreted into fee income over the contractual life of the loan.
Warrants	Warrants In connection with the Company's debt investments, the Company may receive warrants or other equity-related securities from the borrower. The Company determines the cost basis of warrants based upon their respective fair values on the date of receipt in proportion to the total fair value of the debt and warrants received. Any resulting difference between the face amount of the debt and its recorded fair value resulting from the assignment of value to the warrants is treated as original issue discount (“OID”), and accreted into interest income using the effective interest method over the term of the debt investment.
Debt	Debt Issuance Costs Debt issuance costs include commitment fees and other costs related to CSWC’s senior secured credit facility, its unsecured notes (as discussed further in Note 5) and the debentures guaranteed by the SBA (the "SBA Debentures"). The costs in connection with the credit facility have been capitalized and are amortized into interest expense over the term of the credit facility. The costs in connection with the unsecured notes and the SBA Debentures are a direct deduction from the related debt liability and amortized into interest expense over the term of the January 2026 Notes (as defined below), the October 2026 Notes (as defined below) and the SBA Debentures. Deferred Offering Costs Deferred offering costs include registration expenses related to our shelf registration statement and expenses related to the launch of the "at-the-market" ("ATM") program through which we can sell, from time to time, shares of our common stock (the "Equity ATM Program"). These expenses consist primarily of SEC registration fees, legal fees and accounting fees incurred related thereto. These expenses are included in other assets on the Consolidated Statements of Assets and Liabilities. Upon the completion of an equity offering or a debt offering, the deferred expenses are charged to additional paid-in capital or debt issuance costs, respectively. If there are any deferred offering costs remaining at the expiration of the shelf registration statement, these deferred costs are charged to expense. Realized Losses on Extinguishment of Debt Upon the repayment of debt obligations that are deemed to be extinguishments, the difference between the principal amount due at maturity adjusted for any unamortized debt issuance costs is recognized as a loss (i.e., the unamortized debt issuance costs and any "make-whole" premium payment (as discussed in Note 5)) are recognized as a loss upon extinguishment of the underlying debt obligation).
Leases	Leases The Company is obligated under an operating lease pursuant to which it is leasing an office facility from a third party with a remaining term of approximately 10 years. The operating lease is included as an operating lease right-of-use ("ROU") asset and operating lease liability in the accompanying Consolidated Statements of Assets and Liabilities. The Company does not have any financing leases.The ROU asset represents the Company’s right to use an underlying asset for the lease term and the operating lease liability represents the Company’s obligation to make lease payments arising from such lease. Operating lease ROU assets and liabilities are recognized at the commencement date based on the present value of lease payments over the remaining lease term. The Company’s lease does not provide an implicit discount rate, and as such the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of the remaining lease payments. Lease expense is recognized on a straight-line basis over the remaining lease term.
Federal Income Taxes	Federal Income Taxes CSWC has elected, and intends to qualify annually, to be treated for U.S. federal income tax purposes as a RIC under Subsection M of the Code. By meeting these requirements, we will not be subject to U.S. federal income taxes at corporate rates on ordinary income or capital gains timely distributed to shareholders. In order to qualify as a RIC, the Company is required to timely distribute to its shareholders at least 90% of investment company taxable income, as defined by the Code, each year. Investment company taxable income generally differs from net income for financial reporting purposes due to temporary and permanent differences in the recognition of income and expenses. Investment company taxable income generally excludes net unrealized appreciation or depreciation, as investment gains and losses are not included in investment company taxable income until they are realized. Depending on the level of taxable income or capital gains earned in a tax year, we may choose to carry forward taxable income or capital gains in excess of current year distributions into the next year and pay a 4% U.S. federal excise tax on such income. Any such carryover taxable income or capital gains must be distributed through a dividend declared on or prior to the later of (1) the filing of the U.S. federal income tax return for the applicable fiscal year and (2) the fifteenth day of the ninth month following the close of the year in which such taxable income was generated. In lieu of distributing our net capital gains for a year, we may decide to retain some or all of our net capital gains. We will be required to pay a 21% corporate rate U.S. federal income tax on any such retained net capital gains. We may elect to treat such retained capital gain as a deemed distribution to shareholders. Under such circumstances, shareholders will be required to include their share of such retained capital gain in income, but will receive a credit for the amount of U.S. federal income tax paid at corporate rates with respect to their shares. As an investment company that qualifies as a RIC, federal income taxes payable on security gains that we elect to retain are accrued only on the last day of our tax year, December 31. Any net capital gains actually distributed to shareholders and properly reported by us as capital gain dividends are generally taxable to the shareholders as long-term capital gains. See Note 6 for further discussion. The Taxable Subsidiary, a wholly-owned subsidiary of CSWC, is not a RIC and is required to pay taxes at the corporate rate of 21%. For tax purposes, the Taxable Subsidiary has elected to be treated as a taxable entity, and therefore is not consolidated for tax purposes and is taxed at normal corporate tax rates based on taxable income and, as a result of its activities, may generate an income tax provision or benefit. The taxable income, or loss, of the Taxable Subsidiary may differ from its book income, or loss, due to temporary book and tax timing differences and permanent differences. This income tax provision, or benefit, if any, and the related tax assets and liabilities, are reflected in our consolidated financial statements. Management evaluates tax positions taken or expected to be taken in the course of preparing the Company’s consolidated financial statements to determine whether the tax positions are “more-likely-than-not” to be sustained by the applicable tax authority. Tax positions with respect to tax at the CSWC level not deemed to meet the “more-likely-than-not” threshold would be recorded as an expense in the current year. Management’s conclusions regarding tax positions will be subject to review and may be adjusted at a later date based on factors including, but not limited to, on-going analyses of tax laws, regulations and interpretations thereof. The Company has concluded that it does not have any uncertain tax positions that meet the recognition of measurement criteria of ASC 740, Income Taxes, ("ASC 740") for the current period. Also, we account for interest and, if applicable, penalties for any uncertain tax positions as a component of income tax provision. No interest or penalties expense was recorded during the three and six months ended September 30, 2022 and 2021. Deferred Taxes Deferred tax assets and liabilities are recorded for losses or income at our taxable subsidiaries using statutory tax rates. A valuation allowance is provided against deferred tax assets when it is more likely than not that some portion or all of the deferred tax asset will not be realized. ASC 740 requires the effects of changes in tax rates and laws on deferred tax balances to be recognized in the period in which the legislation was enacted. See Note 6 for further discussion.
Stock-Based Compensation	Stock-Based Compensation We account for our share-based compensation using the fair value method, as prescribed by ASC Topic 718, Compensation – Stock Compensation. Accordingly, we recognize share-based compensation cost on a straight-line basis for all share-based payments awards granted to employees. For restricted stock awards, we measure the grant date fair value based upon the market price of our common stock on the date of the grant. For restricted stock awards, we amortize this fair value to share-based compensation expense over the vesting term. We recognize forfeitures as they occur. The unvested shares of restricted stock awarded pursuant to CSWC’s equity compensation plans are participating securities and are included in the basic and diluted earnings per share calculation. The right to grant restricted stock awards under the 2010 Plan terminated on July 18, 2021, ten years after the date that the 2010 Restricted Stock Award Plan (the “2010 Plan”) was approved by the Company’s shareholders pursuant to its terms. In connection with the termination of the 2010 Plan, the Company’s Board of Directors and shareholders approved the Capital Southwest Corporation 2021 Employee Restricted Stock Award Plan (the "2021 Employee Plan"), which became effective on July 28, 2021, as part of the compensation package for its employees, the terms of which are, in all material respects, identical to the 2010 Plan. On July 19, 2021, we received an exemptive order that supersedes the prior exemptive order relating to the 2010 Plan (the “Order”) to permit the Company to (i) issue restricted stock as part of the compensation package for its employees in the 2021 Employee Plan, and (ii) withhold shares of the Company’s common stock or purchase shares of the Company’s common stock from the participants to satisfy tax withholding obligations relating to the vesting of restricted stock pursuant to the 2021 Employee Plan. In addition, the Company's Board of Directors and shareholders approved the Capital Southwest Corporation 2021 Non-Employee Director Restricted Stock Plan (the "Non-Employee Director Plan"), which became effective on July 27, 2022, as part of the compensation package for non-employee directors of the Board of Directors. In connection therewith, on May 16, 2022, we received an exemptive order that supersedes the Order (the "Superseding Order") and covers both employees and non-employee directors of the Board of Directors.
Shareholder Distributions	Shareholder Distributions Distributions to common shareholders are recorded on the ex-dividend date. The amount of distributions, if any, is determined by the Board of Directors each quarter and is generally based upon the earnings estimated by management. Net realized capital gains, if any, are generally distributed, although the Company may decide to retain such capital gains for investment.
Presentation	Presentation Presentation of certain amounts in the consolidated financial statements for the prior year comparative consolidated financial statements is updated to conform to the current period presentation.
Recently Issued or Adopted Accounting Standards	Recently Issued or Adopted Accounting Standards In March 2020, the FASB issued ASU 2020-04, "Reference rate reform (Topic 848)—Facilitation of the effects of reference rate reform on financial reporting." The amendments in this update provide optional expedients and exceptions for applying U.S. GAAP to certain contracts and hedging relationships that reference LIBOR or another reference rate expected to be discontinued due to reference rate reform and became effective upon issuance for all entities. The Company has agreements that have LIBOR as a reference rate with certain portfolio companies and certain lenders. Many of these agreements include an alternative successor rate or language for choosing an alternative successor rate when LIBOR reference is no longer considered to be appropriate. With respect to other agreements, the Company intends to work with its portfolio companies and certain lenders to modify agreements to choose an alternative successor rate. Contract modifications are required to be evaluated in determining whether the modifications result in the establishment of new contracts or the continuation of existing contracts. The standard is effective as of March 12, 2020 through December 31, 2022. The expedients and exceptions provided by the amendments do not apply to contract modifications and hedging relationships entered into or evaluated after December 31, 2022, except for hedging transactions as of December 31, 2022, that an entity has elected certain optional expedients for and that are retained through the end of the hedging relationship. The Company does not believe it will have a material impact on its consolidated financial statements or its disclosure and did not utilize the optional expedients and exceptions provided by ASU 2020-04 during the six months ended September 30, 2022.In June 2022, the FASB issued ASU 2022-03, “Fair Value Measurement (Topic 820) - Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions,” which was issued to (1) clarify the guidance in Topic 820, Fair Value Measurement, when measuring the fair value of an equity security subject to contractual restrictions that prohibit the sale of an equity security, (2) amend a related illustrative example, and (3) introduce new disclosure requirements for equity securities subject to contractual sale restrictions that are measured at fair value in accordance with Topic 820. The new guidance is effective for interim and annual periods beginning after December 15, 2023. The Company is currently evaluating the impact of the new standard on the Company's consolidated financial statements and related disclosures and does not believe it will have a material impact on its consolidated financial statements or its disclosure.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

6 Months Ended

Sep. 30, 2022

The consolidated financial statements have been prepared in accordance with Generally Accepted Accounting Principles in the United States of America (“U.S. GAAP”). We meet the definition of an investment company and follow the accounting and reporting guidance in the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 946 – Financial Services – Investment Companies (“ASC 946”). Under rules and regulations applicable to investment companies, we are generally precluded from consolidating any entity other than another investment company, subject to certain exceptions. One of the exceptions to this general principle occurs if the investment company has an investment in an operating company that provides services to the investment company. Accordingly, the consolidated financial statements include the Taxable Subsidiary.

The consolidated financial statements are presented in conformity with U.S. GAAP for interim financial information and pursuant to the requirements for reporting on Form 10-Q and Article 10 of Regulation S-X. Accordingly, certain disclosures accompanying annual consolidated financial statements prepared in accordance with U.S. GAAP are omitted. In the opinion of our management, the unaudited consolidated financial results included herein contain all adjustments, consisting solely of normal recurring accruals, considered necessary for the fair presentation of consolidated financial statements for the interim periods included herein. The results of operations for the three and six months ended September 30, 2022 are not necessarily indicative of the operating results to be expected for the full fiscal year. Also, the unaudited consolidated financial statements and notes should be read in conjunction with the audited consolidated financial statements and notes thereto for the fiscal years ended March 31, 2022 and 2021. Consolidated financial statements prepared on a U.S. GAAP basis require management to make estimates and assumptions that affect the amounts and disclosures reported in the consolidated financial statements and accompanying notes. Such estimates and assumptions could change in the future as more information becomes known, which could impact the amounts reported and disclosed herein.

Investments

Portfolio Investment Classification

We classify our investments in accordance with the requirements of the 1940 Act. Under the 1940 Act, “Control Investments” are generally defined as investments in which we own more than 25% of the voting securities; “Affiliate Investments” are generally defined as investments in which we own between 5% and 25% of the voting securities, and the investments are not classified as “Control Investments”; and “Non-Control/Non-Affiliate Investments” are generally defined as investments that are neither “Control Investments” nor “Affiliate Investments.”

Under the 1940 Act, a BDC must meet certain requirements, including investing at least 70% of its total assets in qualifying assets. As of September 30, 2022, the Company has 87.1% of its assets in qualifying assets. The principal categories of qualifying assets relevant to our business are:

(1)Securities purchased in transactions not involving any public offering from the issuer of such securities, which issuer (subject to certain limited exceptions) is an "eligible portfolio company," or from any person who is, or has been during the preceding 13 months, an affiliated person of an eligible portfolio company, or from any other person, subject to such rules as may be prescribed by the Securities and Exchange Commission ("SEC").

(2)Securities of any eligible portfolio company that we control.

(3)Securities purchased in a private transaction from a U.S. issuer that is not an investment company or from an affiliated person of the issuer, or in transactions incident thereto, if the issuer is in bankruptcy and subject to reorganization or if the issuer, immediately prior to the purchase of its securities was unable to meet its obligations as they came due without material assistance other than conventional lending or financing arrangements.

(4)Securities of an eligible portfolio company purchased from any person in a private transaction if there is no readily available market for such securities and we already own 60% of the outstanding equity of the eligible portfolio company.

(5)Securities received in exchange for or distributed on or with respect to securities described in (1) through (4) above, or pursuant to the exercise of warrants or rights relating to such securities.

(6)Cash, cash equivalents, U.S. government securities or high-quality debt securities maturing in one year or less from the time of investment.

Additionally, in order to qualify for RIC tax treatment for U.S. federal income tax purposes, we must, among other things meet the following requirements:

(1) Continue to maintain our election as a BDC under the 1940 Act at all times during each taxable year.

(2) Derive in each taxable year at least 90% of our gross income from dividends, interest, payments with respect to certain securities, loans, gains from the sale of stock or other securities, net income from certain "qualified publicly traded partnerships," or other income derived with respect to our business of investing in such stock or securities.

(3) Diversify our holdings in accordance with two Diversification Requirements: (a) Diversify our holdings such that at the end of each quarter of the taxable year at least 50% of the value of our assets consists of cash, cash equivalents, U.S. Government securities, securities of other RICs, and such other securities if such other securities of any one issuer do not represent more than 5% of the value of our assets or more than 10% of the outstanding voting securities of the issuer; and (b) Diversify our holdings such that no more than 25% of the value of our assets is invested in the securities, other than U.S. government securities or securities of other RICs, (i) of one issuer, (ii) of two or more issuers that are controlled, as determined under applicable Code rules, by us and that are engaged in the same or similar or related trades or businesses or (iii) of certain "qualified publicly traded partnerships" (collectively, the "Diversification Requirements").

The two Diversification Requirements must be satisfied quarterly. If a RIC satisfies the Diversification Requirements for one quarter, and then, due solely to fluctuations in market value, fails to meet one of the Diversification Requirements in the next quarter, it retains RIC tax treatment. A RIC that fails to meet the Diversification Requirements as a result of a nonqualified acquisition may be subject to excess taxes unless the nonqualified acquisition is disposed of and the Diversification Requirements are satisfied within 30 days of the close of the quarter in which the Diversification Requirements are failed.

Investments Investments are stated at fair value and are reviewed and approved by our Board of Directors as described in the Notes to the Consolidated Schedule of Investments and Notes 3 and 4 below. Investments are recorded on a trade date basis.

Net Realized Gains or Losses and Net Unrealized Appreciation or Depreciation Realized gains or losses are measured by the difference between the net proceeds from the sale or redemption of an investment or a financial instrument and the cost basis of the investment or financial instrument, without regard to unrealized appreciation or depreciation previously recognized, and includes investments written-off during the period net of recoveries and realized gains or losses from in-kind redemptions. Net unrealized appreciation or depreciation reflects the net change in the fair value of the investment portfolio and financial instruments and the reclassification of any prior period unrealized appreciation or depreciation on exited investments and financial instruments to realized gains or losses.

Investment Valuation Process

The valuation process is led by the finance department in conjunction with the investment team. The process includes a quarterly review of each investment by our executive officers and investment team. Valuations of each portfolio security are prepared quarterly by the finance department using updated financial and other operational information collected by the investment team. Each investment valuation is then subject to review by the executive officers and investment team. In conjunction with the internal valuation process, we have also engaged multiple independent consulting firms specializing in financial due diligence, valuation, and business advisory services to provide third-party valuation reviews of certain investments. The third-party valuation firms provide a range of values for selected investments, which is presented to CSWC’s executive officers and then subsequently to the Board of Directors.

CSWC also uses a standard internal investment rating system in connection with its investment oversight, portfolio management, and investment valuation procedures for its debt portfolio. This system takes into account both quantitative and qualitative factors of the portfolio company and the investments held therein.

There is no single standard for determining fair value in good faith, as fair value depends upon the specific circumstances of each individual investment. While management believes our valuation methodologies are appropriate and consistent with market participants, the recorded fair values of our investments may differ significantly from fair values that would have been used had an active market for the securities existed. In addition, changes in the market environment and other events that may occur over the life of the investments may cause the gains or losses ultimately realized on these investments to be different than the valuations currently assigned. The Board of Directors has the ultimate responsibility for reviewing and determining, in good faith, the fair value of CSWC’s investments in accordance with the 1940 Act.

Fair Value Measurements

Fair Value Measurements We account for substantially all of our financial instruments at fair value in accordance with ASC Topic 820 – Fair Value Measurements and Disclosures (“ASC 820”). ASC 820 defines fair value, establishes a framework used to measure fair value and requires disclosures for fair value measurements, including the categorization of financial instruments into a three-level hierarchy based on the transparency of valuation inputs. ASC 820 requires disclosure of the fair value of financial instruments for which it is practical to estimate such value. We believe that the carrying amounts of our financial instruments such as cash, receivables and payables approximate the fair value of these items due to the short maturity of these instruments. This is considered a Level 1 valuation technique. The carrying value of our credit facility approximates fair value (Level 3 input). See Note 4 below for further discussion regarding the fair value measurements and hierarchy.

Cash and Cash Equivalents

Cash and Cash Equivalents Cash and cash equivalents, which consist of cash and highly liquid investments with an original maturity of three months or less at the date of purchase, are carried at cost, which approximates fair value. Cash may be held in a money market fund from time to time, which is a Level 1 security. Cash and cash equivalents includes deposits at financial institutions. We deposit our cash balances in financial institutions and, at times, such balances may be in excess of the Federal Deposit Insurance Corporation (“FDIC”) insurance limits. At September 30, 2022 and March 31, 2022, cash balances totaling $29.0 million and $10.2 million, respectively, exceeded FDIC insurance limits, subjecting us to risk related to the uninsured balance. All of our cash deposits are held at large established high credit quality financial institutions and management believes that the risk of loss associated with any uninsured balances is remote.

Segment Information

Segment Information We operate and manage our business in a singular segment. As an investment company, we invest in portfolio companies in various industries and geographic areas as discussed in Note 3.

Consolidation

Consolidation As permitted under Regulation S-X and ASC 946, we generally do not consolidate our investment in a portfolio company other than an investment company subsidiary or a controlled operating company whose business consists of providing services to CSWC. Accordingly, we consolidate the results of CSWC’s wholly-owned Taxable Subsidiary and SBIC I. All intercompany balances have been eliminated upon consolidation.

Use of Estimates

Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. We have identified investment valuation and revenue recognition as our most critical accounting estimates.

Interest Income

Interest and Dividend Income Interest and dividend income is recorded on an accrual basis to the extent amounts are expected to be collected. Dividend income is recognized on the date dividends are declared by the portfolio company or at the point an obligation exists for the portfolio company to make a distribution. Discounts/premiums received to par on loans purchased are capitalized and accreted or amortized into income over the life of the loan using the effective interest method. In accordance with our valuation policy, accrued interest and dividend income is evaluated quarterly for collectability. When we do not expect the debtor to be able to service all of its debt or other obligations, we will generally establish a reserve against interest income receivable, thereby placing the loan or debt security on non-accrual status, and cease to recognize interest income on that loan or debt security until the borrower has demonstrated the ability and intent to pay contractual amounts due. If a loan or debt security’s status significantly improves regarding its ability to service debt or other obligations, it will be restored to accrual basis. As of September 30, 2022, investments on non-accrual status represented approximately 0.9% of our total investment portfolio's fair value and approximately 2.3% of its cost. As of March 31, 2022, investments on non-accrual status represented approximately 1.5% of our total investment portfolio's fair value and approximately 2.6% of its cost.

To maintain RIC tax treatment, non-cash sources of income such as accretion of interest income may need to be paid out to shareholders in the form of distributions, even though CSWC may not have collected the interest income. For the three and six months ended September 30, 2022, approximately 3.6% and 3.7%, respectively, of CSWC's total investment income was attributable to non-cash interest income for the accretion of discounts associated with debt investments, net of any premium reduction. For the three and six months ended September 30, 2021, approximately 3.6% and 3.7%, respectively, of CSWC's total investment income was attributable to non-cash interest income for the accretion of discounts associated with debt investments, net of any premium reduction.

Payment-in-Kind Interest The Company currently holds, and expects to hold in the future, some investments in its portfolio that contain payment-in-kind (“PIK”) interest provisions. The PIK interest, computed at the contractual rate specified in each loan agreement, is added to the principal balance of the loan, rather than being paid to the Company in cash, and is recorded as interest income. Thus, the actual collection of PIK interest may be deferred until the time of debt principal repayment. PIK interest, which is a non-cash source of income, is included in the Company’s taxable income and therefore affects the amount the Company is required to distribute to shareholders to maintain its qualification as a RIC for U.S. federal income tax purposes, even though the Company has not yet collected the cash. Generally, when current cash interest and/or principal payments on a loan become past due, or if the Company otherwise does not expect the borrower to be able to service its debt and other obligations, the Company will place the investment on non-accrual status and will generally cease recognizing PIK interest income on that loan for financial reporting purposes until all principal and interest have been brought current through payment or due to a restructuring such that the interest income is deemed to be collectible. The Company writes off any accrued and uncollected PIK interest when it is determined that

the PIK interest is no longer collectible.

Dividends Income

Fee Income

Fee Income Fee income, generally collected in advance, includes fees for administration and valuation services rendered by the Company. These fees are typically charged annually and are amortized into income over the year. The Company recognizes nonrecurring fees, including prepayment penalties, waiver fees and amendment fees, as fee income when earned. In addition, the Company may also be entitled to an exit fee that is amortized into income over the life of the loan. Loan exit fees to be paid at the termination of the loan are accreted into fee income over the contractual life of the loan.

Warrants

Warrants In connection with the Company's debt investments, the Company may receive warrants or other equity-related securities from the borrower. The Company determines the cost basis of warrants based upon their respective fair values on the date of receipt in proportion to the total fair value of the debt and warrants received. Any resulting difference between the face amount of the debt and its recorded fair value resulting from the assignment of value to the warrants is treated as original issue discount (“OID”), and accreted into interest income using the effective interest method over the term of the debt investment.

Debt

Debt Issuance Costs Debt issuance costs include commitment fees and other costs related to CSWC’s senior secured credit facility, its unsecured notes (as discussed further in Note 5) and the debentures guaranteed by the SBA (the "SBA Debentures"). The costs in connection with the credit facility have been capitalized and are amortized into interest expense over the term of the credit facility. The costs in connection with the unsecured notes and the SBA Debentures are a direct deduction from the related debt liability and amortized into interest expense over the term of the January 2026 Notes (as defined below), the October 2026 Notes (as defined below) and the SBA Debentures.

Deferred Offering Costs Deferred offering costs include registration expenses related to our shelf registration statement and expenses related to the launch of the "at-the-market" ("ATM") program through which we can sell, from time to time, shares of our common stock (the "Equity ATM Program"). These expenses consist primarily of SEC registration fees, legal fees and accounting fees incurred related thereto. These expenses are included in other assets on the Consolidated Statements of Assets and Liabilities. Upon the completion of an equity offering or a debt offering, the deferred expenses are charged to additional paid-in capital or debt issuance costs, respectively. If there are any deferred offering costs remaining at the expiration of the shelf registration statement, these deferred costs are charged to expense.

Realized Losses on Extinguishment of Debt Upon the repayment of debt obligations that are deemed to be extinguishments, the difference between the principal amount due at maturity adjusted for any unamortized debt issuance costs is recognized as a loss (i.e., the unamortized debt issuance costs and any "make-whole" premium payment (as discussed in Note 5)) are recognized as a loss upon extinguishment of the underlying debt obligation).

Leases

Leases The Company is obligated under an operating lease pursuant to which it is leasing an office facility from a third party with a remaining term of approximately 10 years. The operating lease is included as an operating lease right-of-use ("ROU") asset and operating lease liability in the accompanying Consolidated Statements of Assets and Liabilities. The Company does not have any financing leases.The ROU asset represents the Company’s right to use an underlying asset for the lease term and the operating lease liability represents the Company’s obligation to make lease payments arising from such lease. Operating lease ROU assets and liabilities are recognized at the commencement date based on the present value of lease payments over the remaining lease term. The Company’s lease does not provide an implicit discount rate, and as such the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of the remaining lease payments. Lease expense is recognized on a straight-line basis over the remaining lease term.

Federal Income Taxes

Federal Income Taxes CSWC has elected, and intends to qualify annually, to be treated for U.S. federal income tax purposes as a RIC under Subsection M of the Code. By meeting these requirements, we will not be subject to U.S.

federal income taxes at corporate rates on ordinary income or capital gains timely distributed to shareholders. In order to qualify as a RIC, the Company is required to timely distribute to its shareholders at least 90% of investment company taxable income, as defined by the Code, each year. Investment company taxable income generally differs from net income for financial reporting purposes due to temporary and permanent differences in the recognition of income and expenses. Investment company taxable income generally excludes net unrealized appreciation or depreciation, as investment gains and losses are not included in investment company taxable income until they are realized.

Depending on the level of taxable income or capital gains earned in a tax year, we may choose to carry forward taxable income or capital gains in excess of current year distributions into the next year and pay a 4% U.S. federal excise tax on such income. Any such carryover taxable income or capital gains must be distributed through a dividend declared on or prior to the later of (1) the filing of the U.S. federal income tax return for the applicable fiscal year and (2) the fifteenth day of the ninth month following the close of the year in which such taxable income was generated.

In lieu of distributing our net capital gains for a year, we may decide to retain some or all of our net capital gains. We will be required to pay a 21% corporate rate U.S. federal income tax on any such retained net capital gains. We may elect to treat such retained capital gain as a deemed distribution to shareholders. Under such circumstances, shareholders will be required to include their share of such retained capital gain in income, but will receive a credit for the amount of U.S. federal income tax paid at corporate rates with respect to their shares. As an investment company that qualifies as a RIC, federal income taxes payable on security gains that we elect to retain are accrued only on the last day of our tax year, December 31. Any net capital gains actually distributed to shareholders and properly reported by us as capital gain dividends are generally taxable to the shareholders as long-term capital gains. See Note 6 for further discussion.

The Taxable Subsidiary, a wholly-owned subsidiary of CSWC, is not a RIC and is required to pay taxes at the corporate rate of 21%. For tax purposes, the Taxable Subsidiary has elected to be treated as a taxable entity, and therefore is not consolidated for tax purposes and is taxed at normal corporate tax rates based on taxable income and, as a result of its activities, may generate an income tax provision or benefit. The taxable income, or loss, of the Taxable Subsidiary may differ from its book income, or loss, due to temporary book and tax timing differences and permanent differences. This income tax provision, or benefit, if any, and the related tax assets and liabilities, are reflected in our consolidated financial statements.

Management evaluates tax positions taken or expected to be taken in the course of preparing the Company’s consolidated financial statements to determine whether the tax positions are “more-likely-than-not” to be sustained by the applicable tax authority. Tax positions with respect to tax at the CSWC level not deemed to meet the “more-likely-than-not” threshold would be recorded as an expense in the current year. Management’s conclusions regarding tax positions will be subject to review and may be adjusted at a later date based on factors including, but not limited to, on-going analyses of tax laws, regulations and interpretations thereof. The Company has concluded that it does not have any uncertain tax positions that meet the recognition of measurement criteria of ASC 740, Income Taxes, ("ASC 740") for the current period. Also, we account for interest and, if applicable, penalties for any uncertain tax positions as a component of income tax provision. No interest or penalties expense was recorded during the three and six months ended September 30, 2022 and 2021.

Deferred Taxes Deferred tax assets and liabilities are recorded for losses or income at our taxable subsidiaries using statutory tax rates. A valuation allowance is provided against deferred tax assets when it is more likely than not that some portion or all of the deferred tax asset will not be realized. ASC 740 requires the effects of changes in tax rates and laws on deferred tax balances to be recognized in the period in which the legislation was enacted. See Note 6 for further discussion.

Stock-Based Compensation

Stock-Based Compensation We account for our share-based compensation using the fair value method, as prescribed by ASC Topic 718, Compensation – Stock Compensation. Accordingly, we recognize share-based compensation cost on a straight-line basis for all share-based payments awards granted to employees. For restricted stock awards, we measure the grant date fair value based upon the market price of our common stock on the date of the grant. For restricted stock awards, we amortize this fair value to share-based compensation expense over the vesting term. We recognize forfeitures as they occur. The unvested shares of restricted stock awarded pursuant to CSWC’s equity compensation plans are participating securities and are included in the basic and diluted earnings per share calculation. The right to grant restricted stock awards under the 2010 Plan terminated on July 18, 2021, ten years after the date that the 2010 Restricted Stock Award Plan (the “2010 Plan”) was approved by the Company’s shareholders pursuant to its terms. In connection with the termination of the 2010 Plan, the Company’s Board of Directors and shareholders approved the Capital Southwest Corporation 2021 Employee Restricted Stock Award Plan (the "2021 Employee Plan"), which became effective on July 28, 2021, as part of the compensation package for its employees, the terms of which are, in all material respects, identical to the 2010 Plan. On July 19, 2021, we received an exemptive order that supersedes the prior exemptive order relating to the 2010 Plan (the “Order”) to permit the Company to (i) issue restricted stock as part of the compensation package for its employees in the 2021 Employee Plan, and (ii) withhold shares of the Company’s common stock or purchase shares of the Company’s common stock from the participants to satisfy tax withholding obligations relating to the vesting of restricted stock pursuant to the 2021 Employee Plan. In addition, the Company's Board of Directors and shareholders approved the Capital Southwest Corporation 2021 Non-Employee Director Restricted Stock Plan (the "Non-Employee Director Plan"), which became effective on July 27, 2022, as part of the compensation package for non-employee directors of the Board of Directors. In connection therewith, on May 16, 2022, we received an exemptive order that supersedes the Order (the "Superseding Order") and covers both employees and non-employee directors of the Board of Directors.

Shareholder Distributions

Shareholder Distributions Distributions to common shareholders are recorded on the ex-dividend date. The amount of distributions, if any, is determined by the Board of Directors each quarter and is generally based upon the earnings estimated by management. Net realized capital gains, if any, are generally distributed, although the Company may decide to retain such capital gains for investment.

Presentation

Presentation Presentation of certain amounts in the consolidated financial statements for the prior year comparative consolidated financial statements is updated to conform to the current period presentation.

Recently Issued or Adopted Accounting Standards

Recently Issued or Adopted Accounting Standards In March 2020, the FASB issued ASU 2020-04, "Reference rate reform (Topic 848)—Facilitation of the effects of reference rate reform on financial reporting." The amendments in this update provide optional expedients and exceptions for applying U.S. GAAP to certain contracts and hedging relationships that reference LIBOR or another reference rate expected to be discontinued due to reference rate reform and became effective upon issuance for all entities. The Company has agreements that have LIBOR as a reference rate with certain portfolio companies and certain lenders. Many of these agreements include an alternative successor rate or language for choosing an alternative successor rate when LIBOR reference is no longer considered to be appropriate. With respect to other agreements, the Company intends to work with its portfolio companies and certain lenders to modify agreements to choose an alternative successor rate. Contract modifications are required to be evaluated in determining whether the modifications result in the establishment of new contracts or the continuation of existing contracts. The standard is effective as of March 12, 2020 through December 31, 2022. The expedients and exceptions provided by the amendments do not apply to contract modifications and hedging relationships entered into or evaluated after December 31, 2022, except for hedging transactions as of December 31, 2022, that an entity has elected certain optional expedients for and that are retained through the end of the hedging relationship. The Company does not believe it will have a material impact on its consolidated financial statements or its disclosure and did not utilize the optional expedients and exceptions provided by ASU 2020-04 during the six months ended September 30, 2022.In June 2022, the FASB issued ASU 2022-03, “Fair Value Measurement (Topic 820) - Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions,” which was issued to (1) clarify the guidance in Topic 820, Fair Value Measurement, when measuring the fair value of an equity security subject to contractual restrictions that prohibit the sale of an equity security, (2) amend a related illustrative example, and (3) introduce new disclosure requirements for equity securities subject to contractual sale restrictions that are measured at fair value in accordance with Topic 820. The new guidance is effective for interim and annual periods beginning after December 15, 2023. The Company is currently evaluating the impact of the new standard on the Company's consolidated financial statements and related disclosures and does not believe it will have a material impact on its consolidated financial statements or its disclosure.