Alector, Inc. Income Taxes Disclosure

9. Income Taxes

In assessing the realization of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred assets will be realized. The ultimate realization of the deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Evaluating the need for a valuation allowance for deferred tax assets often requires judgment and analysis of all the positive and negative evidence available, including cumulative losses in recent years and projected future taxable income, to determine whether all or some portion of the deferred tax assets will not be realized. As of December 31, 2025, the Company has utilized a full valuation allowance to offset the net deferred tax assets as the Company believes it is not more likely than not that the net deferred tax assets will be fully realizable. The valuation allowance for deferred tax assets increased by $42.9 million during the year ended December 31, 2025.

As of December 31, 2025, the Company had federal and state net operating loss (NOL) carryforwards of approximately $375.6 million and $419.1 million, respectively. Federal NOL carryforwards have an indefinite life and deductions cannot exceed 80% of taxable income. State NOL carryforwards will begin to expire as early as 2030, if not utilized, or have an indefinite life. As of December 31, 2025, the Company also had federal and California tax credit carryforward of approximately $39.4 million and $25.3 million, respectively. The federal tax credits will begin to expire in 2041 while the California tax credits have no expiration date.

Generally, utilization of the NOL carryforwards and credits may be subject to an annual limitation due to the ownership change limitations provided by Section 382, which provides for limitations on NOL carryforwards and certain built-in losses following ownership changes, and Section 383, which provides for special limitations on certain excess credits, etc., of the Code, and similar state provisions. Accordingly, the Company’s ability to utilize NOL carryforwards may be limited as the result of such an “ownership change.” The carryforwards could be subject to an annual limitation, resulting in a reduction in the gross deferred tax assets before considering the valuation allowance. Further, a portion of the carryforwards may expire before being applied to reduce future earnings. The Company is not aware of any changes in ownership that would result in material limitations under Section 382 at this time.

If the unrecognized tax benefits for uncertain tax positions as of December 31, 2025, is recognized, there will be no impact to the effective tax rate as the tax benefit would increase the net deferred tax assets, which is currently offset with a full valuation allowance. The Company’s policy is to include interest and penalties related to unrecognized tax benefits, if any, within the provision for taxes in the consolidated statements of operations. The Company accrued interest and penalties of $0.2 million for the year ended December 31, 2025 and of $0.2 million for the year ended December 31, 2024.

The Company recognizes the tax benefit of an uncertain tax position only if it is more likely than not that the position is sustainable upon examination by the taxing authority, based on the technical merits. During the years ended December 31, 2025 and 2024, the Company recorded an uncertain tax position of $1.8 million and $2.7 million, respectively. The income tax provision for the years ended December 31, 2025 included changes to reserves related to prior year uncertain tax provisions of an increase of zero and decrease of zero, respectively. The income tax provision for the years ended December 31, 2024 included changes to reserves related to prior year uncertain tax provisions of an increase of less than $0.1 million and decrease of zero. The Company’s income tax returns generally remain subject to examination by federal and most state tax authorities.

The Company is currently not subject to any federal income tax audits by the IRS but is subject to ongoing tax audits in various state jurisdictions. The statute of limitations for tax liabilities for all years remains open.