Larimar Therapeutics, Inc. Income Taxes Disclosure

During the years ended December 31, 2025, and 2024, the Company recorded no income tax benefits for the net operating losses incurred in each year due to its uncertainty of realizing a benefit from those items.

Changes in the valuation allowance for deferred tax assets during the year ended December 31, 2025 and 2024 related primarily to the increase in net operating loss carryforwards and tax credit carryforwards and a decrease other deferred tax assets associated with a reduction in the Company’s effective state rate. Changes to the valuation allowance were as follows:

As of December 31, 2025, the Company had net operating loss carryforwards that expire for federal, foreign and state income tax purposes of $349.9 million, $1.2 million and $353.5 million, respectively. The federal and state operating losses begin to expire in 2026 and 2030, while the foreign net loss carryforward can be carried forward indefinitely. As of December 31, 2025, the Company had federal net operating loss carryforwards that were generated after December 31, 2017 of $343.9 million that do not expire, however these carryforwards are limited to 80% of the taxable income in any one tax period. The increase in federal net operating losses carryforward is primarily driven by the pre-tax loss for the period and the current year expensing of domestic R&D costs. As of December 31, 2025, the Company also had available tax credit carryforwards for federal and state income tax purposes of $42.0 million which begin to expire in 2039. Utilization of the pre-Merger net operating loss carryforwards attributable to Zafgen, of approximately $33.5 million, are subject to a substantial annual limitation

under Section 382 of the Internal Revenue Code of 1986 due to ownership changes occurred during the tax year associated with the Merger. In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain stockholders or public groups in the stock of a corporation by more than 50% over a three-year period. The ownership changes will limit the amount of pre-merger Zafgen carryforwards that can be utilized annually to offset future taxable income. The Company has reduced their NOL and R&D tax credit deferred tax assets associated with the pre-Merger Zafgen operations as a result of the 382 analysis.

The Company believes that as a result of its merger with Zafgen, its ability to utilize NOLs acquired in the transaction and our other NOLs is expected to be severely limited by Section 382 of the Code. Additionally, the Company’s July 2021, September 2022, February 2024, July 2025 and February 2026 equity transactions could also limit its ability to utilize NOLs in the future. The Company has not conducted a study to assess whether a change of control has occurred or whether there have been multiple changes of control since inception. If the Company experienced a change of control, as defined by Section 382, at any time since inception, utilization of its net operating loss carryforwards or tax credit carryforwards would be subject to an annual limitation under Section 382, which is determined by first multiplying the value of the Company’s stock at the time of the ownership change by the applicable long-term tax-exempt rate, and then could be subject to additional adjustments, as required. Any limitation may result in expiration of a portion of the net operating loss carryforwards or tax credit carryforwards before utilization. Further, until a study is completed, and any limitation is known, no amounts are being presented as an uncertain tax position.

The Tax Cuts and Jobs Act (“TCJA”) required taxpayers to capitalize and amortize research and experimental expenditures under IRC Section 174 for tax years beginning after December 31, 2021. This rule became effective for the Company during the year ended December 31, 2022 and resulted in the capitalization of research and development costs of $69.2 million, $24.5 million and $22.2 million in 2024, 2023 and 2022, respectively. The Company is amortizing these costs for tax purposes over five years if the research and development was performed in the U.S. and over 15 years if the research and development was performed outside the U.S.

On July 4, 2025, Public Law 119-21 was enacted and added new IRC Section 174A, which permanently restores the ability to immediately deduct domestic research and experimental expenditures for tax years beginning after December 31, 2024; the requirement to capitalize and amortize foreign research and experimental expenditures over 15 years was not changed.

As of December 31, 2025 and 2024, the Company’s net deferred tax asset balance before the valuation allowance was $232.8 million and $173.0 million, respectively, and was comprised principally of net operating loss carryforwards, capitalized research and development expenses and tax credit carryforwards. During the years ended December 31, 2025 and 2024, gross deferred tax assets increased due to deferred tax assets acquired as a result of additional net operating loss carryforwards and research and development tax credits generated.

The Company has evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets. Management has considered the Company’s history of cumulative net losses incurred since inception and its lack of commercialization of any products or generation of any revenue from product sales since inception and has concluded that it is more likely than not that the Company will not realize the benefits of the deferred tax assets. Accordingly, a full valuation allowance has been established against the deferred tax assets as of December 31, 2025 and 2024. Management reevaluates the positive and negative evidence at each reporting period.

The Company has not recorded any amounts for unrecognized tax benefits as of December 31, 2025 and 2024. 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 tax years are still open under statute from 2022 to the present. Earlier years may be examined to the extent that tax credit or net operating loss carryforwards are used in future periods. The Company’s policy is to record interest and penalties related to income taxes as part of its income tax provision.