Summary of Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2022
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The accompanying unaudited interim consolidated financial statements include the accounts of Marinus Pharmaceuticals, Inc. (a Delaware corporation) as well as the accounts of Marinus Pharmaceuticals Emerald Limited (an Ireland company incorporated in February 2021), a wholly owned subsidiary requiring consolidation. Marinus Pharmaceuticals Emerald Limited serves as a corporate presence in the European Union for regulatory purposes. The unaudited interim consolidated financial statements included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). Accordingly, they do not include all information and disclosures necessary for a presentation of our financial position, results of operations and cash flows in conformity with generally accepted accounting principles in the U.S. (GAAP) for annual financial statements. In the opinion of management, these unaudited interim consolidated financial statements reflect all adjustments, consisting primarily of normal recurring accruals, necessary for a fair presentation of our financial position and results of operations and cash flows for the periods presented. The results of operations for interim periods are not necessarily indicative of the results for the full year. These unaudited interim consolidated financial statements should be read in conjunction with the audited financial statements for the year ended December 31, 2021 and accompanying notes thereto included in our Annual Report on Form 10-K filed with the SEC on March 24, 2022.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Actual results could differ from such estimates.
Federal Contract Revenue	Federal Contract Revenue We recognize federal contract revenue from the BARDA Contract in the period in which the allowable research and development expenses are incurred, and receivables associated with this revenue are included within accounts receivable on our interim consolidated balance sheets. This revenue is not within the scope of ASC 606 – Revenue from contracts with customers.
Debt Issuance Costs	Debt Issuance Costs Debt issuance costs incurred in connection with Note payable (Note 8) are amortized to interest expense over the term of the respective financing arrangement using the effective-interest method. Debt issuance costs, net of related amortization, are deducted from the carrying value of the related debt.
Contract Liability	Contract Liability When consideration is received, or such consideration is unconditionally due, from a customer prior to completing our performance obligation to the customer under the terms of a contract, a contract liability is recorded. Contract liabilities expected to be recognized as revenue or a reduction of expense within the 12 months following the balance sheet date are classified as current liabilities. Contract liabilities not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as long-term liabilities. In accordance with ASC 210-20, our contract liability is partially offset by a contract asset as further discussed in Note 9.
Collaboration and Licensing Revenue	Collaboration and Licensing Revenue We may enter into collaboration and licensing arrangements for research and development, manufacturing, and commercialization activities with counterparties for the development and commercialization of our product candidates. These arrangements may contain multiple components, such as (i) licenses, (ii) research and development activities, and (iii) the manufacturing of certain material. Payments pursuant to these arrangements may include non-refundable and refundable payments, payments upon the achievement of significant regulatory, development and commercial milestones, sales of product at certain agreed-upon amounts, and royalties on product sales. The amount of variable consideration is constrained until it is probable that the revenue is not at a significant risk of reversal in a future period. In determining the appropriate amount of revenue to be recognized as we fulfill our obligations under a collaboration agreement, we perform the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations, including whether they are capable of being distinct; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue as we satisfy each performance obligation. We must develop estimates and assumptions that require judgment to determine the underlying stand-alone selling price for each performance obligation, which determines how the transaction price is allocated among the performance obligations. The estimation of the stand-alone selling price may include such estimates as forecasted revenues and costs, development timelines, discount rates and probabilities of regulatory and commercial success. We also apply significant judgment when evaluating whether contractual obligations represent distinct performance obligations, allocating transaction price to performance obligations within a contract, determining when performance obligations have been met, assessing the recognition and future reversal of variable consideration and determining and applying appropriate methods of measuring progress for performance obligations satisfied over time.

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2022

Summary of Significant Accounting Policies

Basis of Presentation

The accompanying unaudited interim consolidated financial statements include the accounts of Marinus Pharmaceuticals, Inc. (a Delaware corporation) as well as the accounts of Marinus Pharmaceuticals Emerald Limited (an Ireland company incorporated in February 2021), a wholly owned subsidiary requiring consolidation. Marinus Pharmaceuticals Emerald Limited serves as a corporate presence in the European Union for regulatory purposes. The unaudited interim consolidated financial statements included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). Accordingly, they do not include all information and disclosures necessary for a presentation of our financial position, results of operations and cash flows in conformity with generally accepted accounting principles in the U.S. (GAAP) for annual financial statements. In the opinion of management, these unaudited interim consolidated financial statements reflect all adjustments, consisting primarily of normal recurring accruals, necessary for a fair presentation of our financial position and results of operations and cash flows for the periods presented. The results of operations for interim periods are not necessarily indicative of the results for the full year. These unaudited interim consolidated financial statements should be read in conjunction with the audited financial statements for the year ended December 31, 2021 and accompanying notes thereto included in our Annual Report on Form 10-K filed with the SEC on March 24, 2022.

Use of Estimates

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Actual results could differ from such estimates.

Federal Contract Revenue

Federal Contract Revenue

We recognize federal contract revenue from the BARDA Contract in the period in which the allowable research and development expenses are incurred, and receivables associated with this revenue are included within accounts receivable on our interim consolidated balance sheets. This revenue is not within the scope of ASC 606 – Revenue from contracts with customers.

Debt Issuance Costs

Debt Issuance Costs

Debt issuance costs incurred in connection with Note payable (Note 8) are amortized to interest expense over the term of the respective financing arrangement using the effective-interest method. Debt issuance costs, net of related amortization, are deducted from the carrying value of the related debt.

Contract Liability

Contract Liability

When consideration is received, or such consideration is unconditionally due, from a customer prior to completing our performance obligation to the customer under the terms of a contract, a contract liability is recorded. Contract liabilities expected to be recognized as revenue or a reduction of expense within the 12 months following the balance sheet date are classified as current liabilities. Contract liabilities not expected to be recognized as revenue within

the 12 months following the balance sheet date are classified as long-term liabilities. In accordance with ASC 210-20, our contract liability is partially offset by a contract asset as further discussed in Note 9.

Collaboration and Licensing Revenue

Collaboration and Licensing Revenue

We may enter into collaboration and licensing arrangements for research and development, manufacturing, and commercialization activities with counterparties for the development and commercialization of our product candidates. These arrangements may contain multiple components, such as (i) licenses, (ii) research and development activities, and (iii) the manufacturing of certain material. Payments pursuant to these arrangements may include non-refundable and refundable payments, payments upon the achievement of significant regulatory, development and commercial milestones, sales of product at certain agreed-upon amounts, and royalties on product sales. The amount of variable consideration is constrained until it is probable that the revenue is not at a significant risk of reversal in a future period.

In determining the appropriate amount of revenue to be recognized as we fulfill our obligations under a collaboration agreement, we perform the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations, including whether they are capable of being distinct; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue as we satisfy each performance obligation.

We must develop estimates and assumptions that require judgment to determine the underlying stand-alone selling price for each performance obligation, which determines how the transaction price is allocated among the performance obligations. The estimation of the stand-alone selling price may include such estimates as forecasted revenues and costs, development timelines, discount rates and probabilities of regulatory and commercial success. We also apply significant judgment when evaluating whether contractual obligations represent distinct performance obligations, allocating transaction price to performance obligations within a contract, determining when performance obligations have been met, assessing the recognition and future reversal of variable consideration and determining and applying appropriate methods of measuring progress for performance obligations satisfied over time.