Summary of Significant Accounting Policies	3 Months Ended
Mar. 31, 2025
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	Note 2 – Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”) for Form 10-Q. Accordingly, certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles have been condensed or omitted pursuant to such rules and regulations. The condensed consolidated balance sheet at December 31, 2024 has been derived from the Company’s audited consolidated financial statements as of that date. In the opinion of management, these condensed consolidated financial statements reflect all normal recurring and other adjustments necessary for a fair presentation. These condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024. Operating results for interim periods are not necessarily indicative of operating results for an entire fiscal year or any other future periods. The accompanying unaudited condensed consolidated financial statements include the accounts of ClearSign and its subsidiary. Intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Research and Development The cost of research and development is expensed as incurred. Research and development costs consist of salaries, benefits, share-based compensation, consumables, and consulting fees, including costs to develop and test prototype equipment and parts. Research and development costs have been offset by funds received, if any, from strategic partners in cost sharing, collaborative projects. During the three months ended March 31, 2025 and 2024, the Company received zero and $107 thousand, respectively, from these types of arrangements. Foreign Operations The accompanying unaudited condensed consolidated balance sheets as of March 31, 2025 and December 31, 2024 include assets amounting to approximately $93 thousand and $145 thousand, respectively, relating to the operations of ClearSign Asia Limited. The Beijing registered capital requirement is $350 thousand, which is required to be paid by June 30, 2032, and of which $211 thousand has been paid as of March 31, 2025. On August 22, 2024, the Board authorized management to move forward with filing for dormancy with Chinese regulators to suspend the Company’s Beijing, China operations. A dormancy filing allows the Company to keep its China legal entity in a suspended status for up to three years. The Company can revive its China operations at any time during those three years with minimal cost impact. The dormancy filing became effective as of March 12, 2025. Recently Issued Accounting Pronouncements In December 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”) to enhance the transparency and decision-making usefulness of income tax disclosures by requiring additional information on an entity's tax rate reconciliation, as well as income taxes paid. ASU 2023-09 is effective for our reporting period beginning January 1, 2025. We are currently assessing the impact that the adoption of ASU 2023-09 will have on the disclosures in our annual consolidated financial statements. In November 2024, FASB issued ASU No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40) (“ASU 2024-03”). ASU 2024-03 requires enhanced disclosures about types of expenses, including purchases of inventory, employee compensation, depreciation, and amortization, in commonly presented expense captions. The amendments are effective for fiscal years beginning after December 15, 2026, and interim periods beginning after December 15, 2027, with early adoption permitted. Entities may apply the amendments prospectively or retrospectively to any or all prior periods presented in the financial statements. We are currently evaluating the impact that this guidance will have on the disclosures within our consolidated financial statements. While ASU 2024-03 will impact only our disclosures and not our financial condition and results of operations, we are assessing when we will adopt the ASU 2024-03.

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2025

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies

Note 2 – Summary of Significant Accounting Policies

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”) for Form 10-Q. Accordingly, certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles have been condensed or omitted pursuant to such rules and regulations. The condensed consolidated balance sheet at December 31, 2024 has been derived from the Company’s audited consolidated financial statements as of that date.

In the opinion of management, these condensed consolidated financial statements reflect all normal recurring and other adjustments necessary for a fair presentation. These condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024. Operating results for interim periods are not necessarily indicative of operating results for an entire fiscal year or any other future periods.

The accompanying unaudited condensed consolidated financial statements include the accounts of ClearSign and its subsidiary. Intercompany balances and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Research and Development

The cost of research and development is expensed as incurred. Research and development costs consist of salaries, benefits, share-based compensation, consumables, and consulting fees, including costs to develop and test prototype equipment and parts. Research and development costs have been offset by funds received, if any, from strategic partners in cost sharing, collaborative projects. During the three months ended March 31, 2025 and 2024, the Company received zero and $107 thousand, respectively, from these types of arrangements.

Foreign Operations

The accompanying unaudited condensed consolidated balance sheets as of March 31, 2025 and December 31, 2024 include assets amounting to approximately $93 thousand and $145 thousand, respectively, relating to the operations of ClearSign Asia Limited. The Beijing registered capital requirement is $350 thousand, which is required to be paid by June 30, 2032, and of which $211 thousand has been paid as of March 31, 2025. On August 22, 2024, the Board authorized management to move forward with filing for dormancy with Chinese regulators to suspend the Company’s Beijing, China operations. A dormancy filing allows the Company to keep its China legal entity in a suspended status for up to three years. The Company can revive its China operations at any time during those three years with minimal cost impact. The dormancy filing became effective as of March 12, 2025.

Recently Issued Accounting Pronouncements

In December 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”) to enhance the transparency and decision-making usefulness of income tax disclosures by requiring additional information on an entity's tax rate reconciliation, as well as income taxes paid. ASU 2023-09 is effective for our reporting period beginning January 1, 2025. We are currently assessing the impact that the adoption of ASU 2023-09 will have on the disclosures in our annual consolidated financial statements.

In November 2024, FASB issued ASU No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40) (“ASU 2024-03”). ASU 2024-03 requires enhanced disclosures about types of expenses, including purchases of inventory, employee compensation, depreciation, and amortization, in commonly presented expense captions. The amendments are effective for fiscal years beginning after December 15, 2026, and interim periods beginning after December 15, 2027, with early adoption permitted. Entities may apply the amendments prospectively or retrospectively to any or all prior periods presented in the financial statements. We are currently evaluating the impact that this guidance will have on the disclosures within our consolidated financial statements. While ASU 2024-03 will impact only our disclosures and not our financial condition and results of operations, we are assessing when we will adopt the ASU 2024-03.