15. Income taxes

For the years ended December 31, 2023 and 2022, the Company recorded a current tax provision of $1.4 million and $3.4 million of income tax expense, respectively, which reflects that Company generated taxable income that was not fully offset by the use of net operating loss carryforwards and tax credits. Management has evaluated the positive and negative evidence bearing upon the realizability of the Company’s deferred tax assets and has determined that it is more likely than not that the Company will not recognize the benefits of the deferred tax assets. As a result, the Company has recorded a full valuation allowance at December 31, 2023 and 2022. The valuation allowance increased by $75.0 million in 2023 due to the increase in deferred tax assets, primarily due to increased capitalization of research and development expenditures in 2023. The valuation allowance increased by $82.3 million in 2022.

Additionally, Sections 382 and 383 of the Internal Revenue Code of 1986, as amended, limit a corporation’s ability to utilize tax attributes to the extent the corporation experiences an “ownership change,” generally defined as a greater than 50 percentage point change in ownership, measured by value, among 5% or greater shareholders over a rolling three-year testing period. To the extent a corporation experiences an ownership change, utilization of pre-ownership change tax attributes (e.g., net operating losses and general business tax credits) to offset post-ownership change taxable income or taxes, is subject to an annual limitation, generally calculated as the pre-ownership change equity value of the corporation, subject to certain prescribed adjustments, multiplied by the long-term tax exempt rate published monthly by the Internal Revenue Service. The Company completed a Section 382 study as of December 31, 2023, and determined that historical ownership changes occurred in June 2017, December 2018, and December 2021. In addition, the Company may experience ownership changes in the future as a result of shifts in stock ownership.

As of December 31, 2023 and 2022, the Company had $16.6 million and $120.3 million, respectively, of federal net operating loss carryforwards that do not expire. Additionally, as of December 31, 2023, the Company had $41.3 million of federal and $19.5 million of Massachusetts tax credits that expire starting in 2042 and 2037.

As of December 31, 2023, and 2022, the Company had no uncertain tax positions. The Company recognizes both interest and penalties associated with unrecognized tax benefits as a component of income tax expense. The Company has not recorded any interest or penalties for unrecognized tax benefits since its inception.

The Company filed income tax returns in the United States and the Commonwealth of Massachusetts in all tax years since inception. Tax years beginning in 2020 remain open to examination in these jurisdictions, as carryforward attributes generated in past years may be adjusted in a future period. The IRS has not made any assessments as of December 31, 2023.