Summary of Significant Accounting Policies and Estimates	6 Months Ended
Jun. 30, 2025
Accounting Policies [Abstract]
Summary of Significant Accounting Policies and Estimates	2. Summary of Significant Accounting Policies and Estimates Basis of Presentation These interim statements should be read in conjunction with the historical Consolidated Financial Statements and related notes of Comfort Systems included in the Annual Report on Form 10-K as filed with the Securities and Exchange Commission (“SEC”) for the year ended December 31, 2024 (the “Form 10-K”). The accompanying unaudited consolidated financial statements were prepared using generally accepted accounting principles for interim financial information and the instructions to Form 10-Q and applicable rules of Regulation S-X of the SEC. Accordingly, these financial statements do not include all the footnotes required by generally accepted accounting principles for complete financial statements and should be read in conjunction with the Form 10-K. We believe all adjustments necessary for a fair presentation of these interim statements have been included and are of a normal and recurring nature. The results of operations for interim periods are not necessarily indicative of the results for the full fiscal year. Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles requires the use of estimates and assumptions by management in determining the reported amounts of assets and liabilities, revenue and expenses and disclosures regarding contingent assets and liabilities. Actual results could differ from those estimates. The most significant estimates used in our financial statements affect revenue and cost recognition for construction contracts, self-insurance accruals, accounting for income taxes, fair value accounting for acquisitions and the quantification of fair value for reporting units in connection with our goodwill impairment testing. Recent Accounting Pronouncements Recent Accounting Pronouncements Not Yet Adopted In December 2023, the FASB issued ASU 2023-09, “Income Taxes (Topic 740): Improvements to Income Tax Disclosures.” This standard requires entities to disclose more detailed information in the reconciliation of their statutory tax rate to their effective tax rate. The standard also requires entities to make additional disclosures on income taxes paid as well as on certain income statement-related disclosures. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024. We will adopt this standard in our 2025 Form 10-K. Entities may apply the standard prospectively or may elect retrospective application. This standard will not have an impact on our consolidated financial position, results of operations or cash flows, but will affect our financial statement disclosures as discussed above. In November 2024, the FASB issued ASU 2024-03, “Income Statement – Reporting Comprehensive Income – Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses.” The standard requires entities to disclose, on an annual and interim basis, disaggregated information about certain income statement expense line items in the notes to the financial statements. ASU 2024-03 is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. Entities may apply the standard prospectively or may elect retrospective application. We are currently evaluating the impact ASU 2024-03 will have on our disclosures; however, the standard will not have an impact on our consolidated financial position, results of operations or cash flows. Revenue Recognition We recognize revenue over time for all of our services as we perform them because (i) control continuously transfers to the customer as work progresses, and (ii) we have the right to bill the customer as costs are incurred. The customer typically controls the work in process, as evidenced either by contractual termination clauses or by our rights to payment for work performed to date, plus a reasonable profit, for delivery of products or services that do not have an alternative use to the Company. For the reasons listed above, revenue is recognized based on the extent of progress towards completion of the performance obligation. The selection of the method to measure progress towards completion requires judgment and is based on the nature of the products or services to be provided. We generally use a cost-to-cost input method to measure our progress towards satisfaction of the performance obligation for our contracts, as it best depicts the transfer of assets to the customer that occurs as we incur costs on our contracts. Under the cost-to-cost input method, the extent of progress towards completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation. Revenue, including estimated fees or profits, is recorded proportionally as costs are incurred. Costs to fulfill include labor, materials, subcontractors’ costs, other direct costs and an allocation of indirect costs. For a small portion of our business in which our services are delivered in the form of service maintenance agreements for existing systems to be repaired and maintained, as opposed to constructed, our performance obligation is to maintain the customer’s mechanical system for a specific period of time. As with construction jobs, we recognize revenue over time; however, for service maintenance agreements in which the full cost to provide services may not be known, we generally use an input method to recognize revenue, which is based on the amount of time we have provided our services out of the total time we have been contracted to perform those services. Our revenue recognition policy is further discussed in Note 3 “Revenue from Contracts with Customers.” Accounts Receivable and Allowance for Credit Losses We are required to estimate and record the expected credit losses over the contractual life of our financial assets measured at amortized cost, including billed and unbilled accounts receivable, other receivables and contract assets. Accounts receivable include amounts from work completed in which we have billed or have an unconditional right to bill our customers. Our trade receivables are contractually due in less than a year. We estimate our credit losses using a loss-rate method for each of our identified portfolio segments. Our portfolio segments are construction, service and other. While our construction and service financial assets are often with the same subset of customers and industries, our construction financial assets will generally have a lower loss-rate than service financial assets due to lien rights, which we are more likely to have on construction jobs. These lien rights result in lower credit loss expenses on average compared to receivables that do not have lien rights. Financial assets classified as “other” include receivables that are not related to our core revenue producing activities, such as receivables related to our acquisition activity from former owners, our vendor rebate program or receivables for estimated losses in excess of our insurance deductible, which are accrued with a corresponding accrued insurance liability. Loss rates for our portfolios are based on numerous factors, including our history of credit loss expense by portfolio, the financial strength of our customers and counterparties in each portfolio, the aging of our receivables, our expectation of likelihood of payment, macroeconomic trends in the U.S. and the current and forecasted nonresidential construction market trends in the U.S. In addition to the loss-rate calculations discussed above, we also record allowance for credit losses for specific receivables that are deemed to have a higher risk profile than the rest of the respective pool of receivables (e.g., when we hold concerns about a specific customer going bankrupt and no longer being able to pay the receivables due to us). Unbilled Accounts Receivable Unbilled accounts receivable are amounts due to us that we have earned under a contract where our right to payment is unconditional. A right to consideration is unconditional if only the passage of time is required before payment of the consideration is due. These items are expected to be billed and collected in the normal course of business. Other unbilled receivables where payment is subject to factors beyond just the passage of time are included in contract assets. Income Taxes We conduct business throughout the United States in virtually all fifty states. Our effective tax rate changes based upon our relative profitability, or lack thereof, in the federal and various state jurisdictions with differing tax rates and rules. In addition, discrete items such as tax law changes, judgments and legal structures, can impact our effective tax rate. These items can also include the tax treatment for impairment of goodwill and other intangible assets, changes in fair value of acquisition-related assets and liabilities, uncertain tax positions, and accounting for losses associated with underperforming operations. In early September 2023, the Internal Revenue Service issued interim guidance addressing, together with other topics, the treatment of research and experimental (“R&E”) expenditures for taxpayers using the percentage of completion method to account for taxable income from long-term contracts. We relied on such guidance for the 2022 tax year, and the resulting reduction in taxable revenue offsets the deferral of tax deductions for R&E expenditures pursuant to the Tax Cuts and Jobs Act (2017) for the 2022 tax year. We filed our 2022 federal tax return in October 2023 requesting a refund of our $107.1 million overpayment, which was received in April 2025. Along with the refund, we received $11.3 million (or $8.9 million, net of tax) of interest income that reduced our provision for income taxes in the first quarter of 2025. The One Big Beautiful Bill Act was enacted into law on July 4, 2025. The primary provisions of the law that will impact us are the (i) reinstatement of immediate expensing of domestic R&E expenditures, together with conforming amendments to the credit for increasing research activities (“R&D tax credit”), (ii) reinstatement of 100% bonus depreciation, and (iii) termination of the energy efficient commercial buildings deduction (“179D deduction”). However, we believe these provisions will not have a material effect on our future operating results, cash flows or financial condition. Financial Instruments Our financial instruments consist of cash and cash equivalents, U.S. Treasury bills, accounts receivable, other receivables and accounts payable, for which we deem the carrying values approximate their fair values due to the short-term nature of these instruments, as well as notes to former owners and a revolving credit facility. Investments As of June 30, 2025, we have a $7.4 million investment in U.S. Treasury bills with maturities greater than ninety days but less than one year, which is recorded at amortized cost and is included in “Prepaid Expenses and Other” in our Consolidated Balance Sheet.

Summary of Significant Accounting Policies and Estimates

6 Months Ended

Jun. 30, 2025

Summary of Significant Accounting Policies and Estimates

2. Summary of Significant Accounting Policies and Estimates

Basis of Presentation

These interim statements should be read in conjunction with the historical Consolidated Financial Statements and related notes of Comfort Systems included in the Annual Report on Form 10-K as filed with the Securities and Exchange Commission (“SEC”) for the year ended December 31, 2024 (the “Form 10-K”).

The accompanying unaudited consolidated financial statements were prepared using generally accepted accounting principles for interim financial information and the instructions to Form 10-Q and applicable rules of Regulation S-X of the SEC. Accordingly, these financial statements do not include all the footnotes required by generally accepted accounting principles for complete financial statements and should be read in conjunction with the Form 10-K. We believe all adjustments necessary for a fair presentation of these interim statements have been included and are of a normal and recurring nature. The results of operations for interim periods are not necessarily indicative of the results for the full fiscal year.

Use of Estimates

The preparation of financial statements in conformity with generally accepted accounting principles requires the use of estimates and assumptions by management in determining the reported amounts of assets and liabilities, revenue and expenses and disclosures regarding contingent assets and liabilities. Actual results could differ from those estimates. The most significant estimates used in our financial statements affect revenue and cost recognition for construction contracts, self-insurance accruals, accounting for income taxes, fair value accounting for acquisitions and the quantification of fair value for reporting units in connection with our goodwill impairment testing.

Recent Accounting Pronouncements

Recent Accounting Pronouncements Not Yet Adopted

In December 2023, the FASB issued ASU 2023-09, “Income Taxes (Topic 740): Improvements to Income Tax Disclosures.” This standard requires entities to disclose more detailed information in the reconciliation of their statutory tax rate to their effective tax rate. The standard also requires entities to make additional disclosures on income taxes paid as well as on certain income statement-related disclosures. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024. We will adopt this standard in our 2025 Form 10-K. Entities may apply the standard prospectively or may elect retrospective application. This standard will not have an impact on our consolidated financial position, results of operations or cash flows, but will affect our financial statement disclosures as discussed above.

In November 2024, the FASB issued ASU 2024-03, “Income Statement – Reporting Comprehensive Income – Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses.” The standard

requires entities to disclose, on an annual and interim basis, disaggregated information about certain income statement expense line items in the notes to the financial statements. ASU 2024-03 is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. Entities may apply the standard prospectively or may elect retrospective application. We are currently evaluating the impact ASU 2024-03 will have on our disclosures; however, the standard will not have an impact on our consolidated financial position, results of operations or cash flows.

Revenue Recognition

We recognize revenue over time for all of our services as we perform them because (i) control continuously transfers to the customer as work progresses, and (ii) we have the right to bill the customer as costs are incurred. The customer typically controls the work in process, as evidenced either by contractual termination clauses or by our rights to payment for work performed to date, plus a reasonable profit, for delivery of products or services that do not have an alternative use to the Company.

For the reasons listed above, revenue is recognized based on the extent of progress towards completion of the performance obligation. The selection of the method to measure progress towards completion requires judgment and is based on the nature of the products or services to be provided. We generally use a cost-to-cost input method to measure our progress towards satisfaction of the performance obligation for our contracts, as it best depicts the transfer of assets to the customer that occurs as we incur costs on our contracts. Under the cost-to-cost input method, the extent of progress towards completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation. Revenue, including estimated fees or profits, is recorded proportionally as costs are incurred. Costs to fulfill include labor, materials, subcontractors’ costs, other direct costs and an allocation of indirect costs.

For a small portion of our business in which our services are delivered in the form of service maintenance agreements for existing systems to be repaired and maintained, as opposed to constructed, our performance obligation is to maintain the customer’s mechanical system for a specific period of time. As with construction jobs, we recognize revenue over time; however, for service maintenance agreements in which the full cost to provide services may not be known, we generally use an input method to recognize revenue, which is based on the amount of time we have provided our services out of the total time we have been contracted to perform those services. Our revenue recognition policy is further discussed in Note 3 “Revenue from Contracts with Customers.”

Accounts Receivable and Allowance for Credit Losses

We are required to estimate and record the expected credit losses over the contractual life of our financial assets measured at amortized cost, including billed and unbilled accounts receivable, other receivables and contract assets. Accounts receivable include amounts from work completed in which we have billed or have an unconditional right to bill our customers. Our trade receivables are contractually due in less than a year.

We estimate our credit losses using a loss-rate method for each of our identified portfolio segments. Our portfolio segments are construction, service and other. While our construction and service financial assets are often with the same subset of customers and industries, our construction financial assets will generally have a lower loss-rate than service financial assets due to lien rights, which we are more likely to have on construction jobs. These lien rights result in lower credit loss expenses on average compared to receivables that do not have lien rights. Financial assets classified as “other” include receivables that are not related to our core revenue producing activities, such as receivables related to our acquisition activity from former owners, our vendor rebate program or receivables for estimated losses in excess of our insurance deductible, which are accrued with a corresponding accrued insurance liability.

Loss rates for our portfolios are based on numerous factors, including our history of credit loss expense by portfolio, the financial strength of our customers and counterparties in each portfolio, the aging of our receivables, our expectation of likelihood of payment, macroeconomic trends in the U.S. and the current and forecasted nonresidential construction market trends in the U.S.

In addition to the loss-rate calculations discussed above, we also record allowance for credit losses for specific receivables that are deemed to have a higher risk profile than the rest of the respective pool of receivables (e.g., when we hold concerns about a specific customer going bankrupt and no longer being able to pay the receivables due to us).

Unbilled Accounts Receivable

Unbilled accounts receivable are amounts due to us that we have earned under a contract where our right to payment is unconditional. A right to consideration is unconditional if only the passage of time is required before payment of the consideration is due. These items are expected to be billed and collected in the normal course of business. Other unbilled receivables where payment is subject to factors beyond just the passage of time are included in contract assets.

Income Taxes

We conduct business throughout the United States in virtually all fifty states. Our effective tax rate changes based upon our relative profitability, or lack thereof, in the federal and various state jurisdictions with differing tax rates and rules. In addition, discrete items such as tax law changes, judgments and legal structures, can impact our effective tax rate. These items can also include the tax treatment for impairment of goodwill and other intangible assets, changes in fair value of acquisition-related assets and liabilities, uncertain tax positions, and accounting for losses associated with underperforming operations.

In early September 2023, the Internal Revenue Service issued interim guidance addressing, together with other topics, the treatment of research and experimental (“R&E”) expenditures for taxpayers using the percentage of completion method to account for taxable income from long-term contracts. We relied on such guidance for the 2022 tax year, and the resulting reduction in taxable revenue offsets the deferral of tax deductions for R&E expenditures pursuant to the Tax Cuts and Jobs Act (2017) for the 2022 tax year. We filed our 2022 federal tax return in October 2023 requesting a refund of our $107.1 million overpayment, which was received in April 2025. Along with the refund, we received $11.3 million (or $8.9 million, net of tax) of interest income that reduced our provision for income taxes in the first quarter of 2025.

The One Big Beautiful Bill Act was enacted into law on July 4, 2025. The primary provisions of the law that will impact us are the (i) reinstatement of immediate expensing of domestic R&E expenditures, together with conforming amendments to the credit for increasing research activities (“R&D tax credit”), (ii) reinstatement of 100% bonus depreciation, and (iii) termination of the energy efficient commercial buildings deduction (“179D deduction”). However, we believe these provisions will not have a material effect on our future operating results, cash flows or financial condition.

Financial Instruments

Our financial instruments consist of cash and cash equivalents, U.S. Treasury bills, accounts receivable, other receivables and accounts payable, for which we deem the carrying values approximate their fair values due to the short-term nature of these instruments, as well as notes to former owners and a revolving credit facility.

Investments

As of June 30, 2025, we have a $7.4 million investment in U.S. Treasury bills with maturities greater than ninety days but less than one year, which is recorded at amortized cost and is included in “Prepaid Expenses and Other” in our Consolidated Balance Sheet.