Multi-Year ISO Exercise Schedule Calculator (2026)

This calculator finds the multi-year incentive stock option (ISO) exercise schedule that maximizes the after-tax value of your grant. It accounts for the alternative minimum tax (AMT) in each exercise year, the AMT credit you recover in later years, and your stock's volatility across the planning horizon. You enter the grant (shares, strike, current fair market value), your income, your filing status, and your state; it returns a year-by-year plan with the tax bill and net value of every year. It also handles the 90-day post-termination exercise window if you have already left the company.

Most AMT tools are single-year estimators. They answer one question: if you exercise this many shares this year, what is this year's AMT hit. That number is useful, and this calculator reports it too, as your AMT crossover. What a single-year estimate cannot tell you is whether splitting the exercise across two, three, or five tax years beats exercising now. That answer depends on what a one-year view never sees: the AMT exemption resets every January, the AMT credit pays you back only in years when your regular tax runs above the tentative minimum, and the stock can move while you wait. This calculator scores complete schedules against all of it and returns the one that ends with the most after-tax value.

The calculator is free and requires no account. If you only need this year's number, the crossover line gives it in one read; the schedule under it is what the single-year tools leave out. The tax math behind both is independently verified: every 2026 federal constant matches IRS Rev. Proc. 2025-32, and federal and state results are reproduced against outside reference calculators, with the proof recomputed live on the verification page.

Optimization. Searches the multi-year ISO exercise space via chunk-grid plus one-share refinement, scoring every candidate schedule against federal and state AMT (with credit recovery), regular tax, and long-term capital gains at horizon. Returns the grid-optimal share-per-year plan. The search is deterministic: the same inputs on the same date return the same answer, so the recommendation is verifiable.

Tax-code coverage. Relevant federal code (ordinary brackets, long-term capital gains, AMT with credit recovery, FICA, Net Investment Income Tax) plus all 50 states and DC for state ordinary brackets and LTCG treatment. State AMT modeled for CA, CO, CT, MN. Brackets reflect IRS Rev. Proc. 2025-32 and the One Big Beautiful Bill Act (OBBBA) provisions for tax year 2026. Validated against 870+ unit tests covering bracket math, AMT credit recovery, state conformity, and the optimizer's search path.

Why use an optimizer rather than asking an LLM to do the math: a benchmark of five frontier large language models on the same multi-year ISO problem found that all 15 trials overstated the after-tax result of their own proposed schedule by 2x to 20x (HackerNoon write-up).