The proof, before you trust the answer

The single most common worry is that a page like this shows hand-picked, hardcoded numbers. So the headline figure is fetched live: when this page loads, your browser posts a real multi-year incentive stock option (ISO) case to the public production application programming interface (API) and reads back the answer. The optimized plan it returns, reported below as its after-tax Net Final Value (NFV), matches the value plotted in section 5 to the cent.

{
  "shares": 4000,
  "strike": 1,
  "fmv": 60,
  "filingStatus": "single",
  "ordinaryIncome": 300000,
  "stateCode": "CA",
  "carryforwardCredit": 0,
  "horizon": 2,
  "cashReturnRate": 0.04,
  "grantDate": "2023-01-01",
  "hasLeftCompany": false,
  "terminationDate": null,
  "expectedGrowth": 0.1,
  "volatility": 0.5
}

The calculators do not estimate the brackets and thresholds; they use the figures the IRS published for tax year 2026. Each value below is read directly from the production tax library and shown beside its source. A separate conformance test asserts every one of these against its published value and fails the build if a single digit drifts.

Primary source: IRS Rev. Proc. 2025-32 (including the One Big Beautiful Bill amendments), Form 6251, and the Internal Revenue Code sections cited above.

Matching the published constants is necessary but not sufficient; the arithmetic on top of them has to be right too. So we cross-check against PSL Tax-Calculator, an open-source federal individual-income tax model maintained independently of OptionsAhoy. Across 14 worked federal cases spanning ordinary income tax, long-term capital gains (the 0 / 15 / 20 percent stack plus the Net Investment Income Tax), and the Alternative Minimum Tax (AMT, including the ISO bargain element), the two engines agree to the cent.

All 14 cases agree to the cent. PSL Tax-Calculator 6.6.2. taxcalc standard deduction set to 0 (OptionsAhoy models ordinaryIncome as taxable income); ISO bargain element fed as cmbtp; marginal capital-gains figure is the iitax delta (taxcalc iitax already includes NIIT). All other 2026-law parameters are taxcalc defaults, which match the published Rev. Proc. 2025-32 / OBBBA figures exactly.

Federal tax is only part of an equity decision; for most holders the state bill is the larger swing. So the state rate schedules are cross-checked the same way, against OpenTaxSolver, an open-source tax program that encodes each state's official rate schedule and is maintained independently of OptionsAhoy. Across the five states that carry the most equity compensation, CA, NY, NJ, PA, MA, the marginal tax OptionsAhoy computes on a sale matches the independent engine to the cent.

All 16 cases agree to the cent. OpenTaxSolver 2025_23.06, tax year 2025. The comparison is at the state rate schedule (the marginal bracket math); each schedule is also confirmed against the state's official publication.

For a deliberately small two-year case, the entire decision is one number: how many of the 4,000 shares to exercise in year one (the rest fall in year two). That lets us brute-force every possibility at single-share resolution and plot the after-tax Net Final Value (NFV). The schedule the optimizer recommends sits on the peak of that curve, above both naive baselines.

Optimizer pick: 1,880 shares in year one, $132,991.44. That is identical to the single-share brute-force maximum, and $18,606.48 ahead of exercising everything now. On real multi-year grants the space is far larger than a person can enumerate by hand, which is the entire point of the tool.

Beyond specific cases, the engine is checked against properties that have to be true for any input. These run on every build:

• The optimized plan is never worse than exercising everything now or splitting evenly.
• Exercising more shares never reduces the gross gain before tax.
• Alternative Minimum Tax credit recovered never exceeds the credit earned.
• At the crossover share count, tentative minimum tax equals the regular tax, by construction.
• Out-of-range or malformed inputs return a clear error with the offending field named, never a wrong number.

None of this requires trusting a screenshot. The calculation engine is open source under the MIT license at github.com/AlvisoOculus/optionsahoy-mcp. The independent cross-checks above are produced by committed scripts that anyone can run against PSL Tax-Calculator (federal) and OpenTaxSolver (state); the federal and state agreement, the constant conformance, and the optimizer ground-truth check are all enforced by the automated test suite, so the claims on this page cannot silently go stale. You can also re-run the live API call yourself with the payload shown in section 1.

References: IRS Rev. Proc. 2025-32 · IRS Form 6251 · PSL Tax-Calculator · methodology