Use a Washington ISO AMT calculator to find how many incentive stock options you can exercise before federal AMT kicks in. Washington has no state income tax, so AMT is the whole tax story at exercise — the bargain element drives a federal bill that state rates never touch.
Calculate Your ISO AMT
Use our ISO AMT Calculator to find the optimal number of shares to exercise without triggering AMT.
Try Calculator →Open the Washington ISO AMT calculator with these inputs prefilled →
How the Washington ISO AMT calculator treats your exercise
Washington has no personal income tax, so exercising incentive stock options creates no Washington state tax at exercise — not on the bargain element, not on regular income. That is why every "state tax impact" line below is $0. The entire tax cost of an ISO exercise in Washington is federal alternative minimum tax (AMT). The one Washington wrinkle comes later: a 7% capital gains tax applies to long-term gains above $270,000 in a year when you sell shares, per the Washington Department of Revenue. It does not apply at exercise.
The federal AMT calculation has three moving parts (IRS Form 6251):
- The bargain element —
(FMV − strike) × shares exercised— is added to your AMT income for the year. - The AMT exemption is subtracted (a fixed amount that phases out at high incomes).
- The remainder is taxed at 26% up to $239,100 of AMT income, then 28% above (2025 thresholds; 2026 figures publish in late 2025).
Because there is no Washington overlay, the federal AMT figure is your full incremental tax at exercise. That makes finding your AMT-free exercise limit the single most valuable number on this page — there is no state credit, no state deduction, and no state tax to plan around at the exercise step.
Worked examples (Washington, 2025)
Each example shows how many ISOs you can exercise before AMT kicks in, using the EquityTax engine. Numbers match what the calculator returns for the inputs shown.
Example 1 — early-stage, single filer
Inputs: $185K W-2 salary, single filer, 10,000 vested ISOs, $2 strike, $12 FMV.
Result:
- Federal regular tax (without ISO exercise): $33,467
- Federal AMT after a full ISO exercise: $17,727
- Washington state tax impact: $0
- Cash needed to exercise all shares (estimate): $20,000 exercise cost plus $17,727 AMT
- AMT-free exercise limit: 3,181 shares
Run this scenario in the calculator →
Example 2 — mid-stage, married filing jointly
Inputs: $255K W-2 salary, married filing jointly, 20,000 vested ISOs, $2 strike, $40 FMV.
Result:
- Federal regular tax: $39,334
- Federal AMT after a full exercise: $201,724
- Washington state tax impact: $0
- Cash needed to exercise all shares: $40,000 exercise cost plus $201,724 AMT
- AMT-free exercise limit: 875 shares
Run this scenario in the calculator →
Example 3 — late-stage, married filing jointly
Inputs: $360K W-2 salary, married filing jointly, 30,000 vested ISOs, $2 strike, $120 FMV.
Result:
- Federal regular tax: $64,534
- Federal AMT after a full exercise: $1,022,684
- Washington state tax impact: $0
- Cash needed to exercise all shares: $60,000 exercise cost plus $1,022,684 AMT
- AMT-free exercise limit: 208 shares
Run this scenario in the calculator →
Notice how the AMT-free limit collapses as FMV climbs: 3,181 shares at a $12 FMV, 875 shares at $40, and just 208 shares at $120. The higher the spread between strike and FMV, the fewer shares it takes to cross into AMT — even though Washington never adds a dime of state tax.
Strategies for Washington option holders
The single biggest lever is timing. Splitting an exercise across two tax years can keep both years below the AMT crossover and turn a five-figure tax bill into a small one — sometimes zero.
- Find your AMT-free limit for this year, exercise at most that number, and roll the rest into next year's exercise window.
- If the bargain element is small, exercise everything that's vested and start the long-term capital gains clock.
- If you exit a startup mid-year, model the post-IPO scenario — the AMT-free limit shrinks fast as FMV climbs, as Example 3 shows.
Washington's lack of income tax means there is no state estimated-tax payment to make at exercise — but plan for the 7% capital gains tax if you later sell long-term shares with gains above $270,000 in a single year.
Open the calculator with your inputs →
Frequently asked questions
Does Washington tax ISO exercises?
No. Washington has no personal income tax, so exercising ISOs creates no Washington state tax — the only tax at exercise is federal AMT. That is why each worked example above shows a $0 Washington state tax impact.
How many ISOs can I exercise before AMT in Washington?
It depends on your income, filing status, and the spread between strike and FMV. In the examples above the AMT-free limit ranges from 3,181 shares (single, $12 FMV) down to 208 shares (married filing jointly, $120 FMV). Run your own numbers in the calculator to get your exact limit.
Will I owe any Washington tax when I sell the shares?
Possibly. Washington applies a 7% tax on long-term capital gains above $270,000 in a year when you sell, per the Washington Department of Revenue. It does not apply at exercise, only at sale.
Sources
- IRS Form 6251, Alternative Minimum Tax (Individuals) — exemption amounts, phase-out thresholds, AMT rates.
- IRS Publication 525, Taxable and Nontaxable Income — ISO bargain-element treatment.
- Washington Revenue Department — state ISO and AMT guidance.
- EquityTax Washington ISO AMT Calculator (internal engine, last verified 2026-05-09).
Tax Disclaimer: This content is for educational purposes only. Always consult with a licensed tax professional or certified public accountant before making financial decisions related to equity compensation, tax planning, or investment strategies.
Estimate only — not financial or tax advice. Consult a qualified CPA before making decisions about exercising stock options, selling equity, or other financial moves.