Solid Biosciences Inc. Income Taxes Disclosure

14. Income Taxes

The Company established deferred tax assets and liabilities on identified book to tax temporary differences as of the date of conversion to a C-corporation. Deferred income taxes reflect the net tax effects of these temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The significant components of the Company’s net deferred tax assets are as follows:

As of December 31, 2025, the Company had federal net operating loss carryforwards of $262.7 million which may be available to offset future taxable income and do not expire but are limited in their usage to an annual deduction equal to 80% of annual taxable income. In addition, as of December 31, 2025, the Company had state net operating loss carryforwards of approximately $261.4 million which may be available to offset future taxable income, of which $257.6 million begins to expire in 2032 and $3.8 million has unlimited carryforward. The Company also had federal and state tax credits of $27.8 million and $5.1 million, respectively, which may be used to offset future tax liability and each of which begin to expire in 2037.

The Company’s ability to utilize these federal and state carryforwards may be limited in the future if the Company experiences an ownership change pursuant to Section 382 of the Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”). Ownership changes, as defined in the Internal Revenue Code, including those resulting from the issuance of

common stock in connection with the Company’s public offerings, may limit the amount of net operating loss and tax credit carryforwards that can be utilized to offset future taxable income or tax liability. The Company completed a study in 2023 to assess whether a change of control had occurred under Section 382, and it was determined that all net operating loss carryforwards and credits generated before December 2, 2022 are limited. As a result, the carryforwards before the ownership change date of December 2, 2022 are not available for utilization and have been written off. The carryforwards as of December 31, 2025 were generated after the ownership change of December 2, 2022.

A valuation allowance is recorded against deferred tax assets if it is more likely than not that some or all of the deferred tax assets will not be realized. The Company has evaluated the positive and negative evidence bearing upon the realizability of the deferred tax assets. The Company concluded, in accordance with the applicable accounting standards, that it is more likely than not that the Company will be unable to realize the benefit of its deferred tax assets. Accordingly, the Company has recorded a full valuation allowance against its deferred tax assets.

The Company files tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. There are currently no pending income tax examinations. The Company’s C-Corporation tax years beginning with the year ended December 31, 2021 are open under statute. Any tax credit or net operating loss carryforward can be adjusted in future periods after the respective year of generation’s statute of limitation has closed.

As of December 31, 2025 and 2024, the Company did not have unrecognized tax benefits. The Company recognizes interest and penalties related to income taxes as a component of income tax expense. As of December 31, 2025 and 2024, no interest and penalties have been recorded.