ISO Alternative Minimum Tax 2026: The Exact Income Level Where AMT Hits Tech Employees

AMT is a parallel tax system — and ISOs are its biggest trigger for tech employees

The Alternative Minimum Tax under IRC § 55 is a shadow tax calculation that runs alongside your regular federal income tax every year. You compute both. You pay whichever is higher. For most W-2 employees, regular tax wins and AMT is irrelevant. But the moment you exercise incentive stock options without selling the shares, AMT can leap ahead — because ISOs create an AMT preference item that regular tax ignores entirely.

Here’s the disconnect: under regular tax rules (IRC § 421), exercising ISOs is not a taxable event. You exercise at $10, the stock is worth $40, you owe nothing to the IRS until you sell. Under AMT rules (IRC § 56(b)(3)), that $30 spread × every share exercised is added to your AMT income in the year of exercise. The IRS treats the spread as if you received $30 per share of phantom income — income you never saw in cash, can’t spend, and might evaporate if the stock drops.

This is not a theoretical risk. In 2000–2001, thousands of tech employees exercised ISOs at peak valuations, owed six-figure AMT bills, then watched the stock collapse. They still owed the AMT. Some faced personal bankruptcy over a tax bill on gains that no longer existed. The AMT credit (discussed below) helps over time, but it doesn’t help in the year you owe $78,000 on shares that just lost 60% of their value.

2026 AMT exemption and phase-out: the exact numbers

The AMT exemption is the amount of AMT income you can earn before the 26%/28% AMT rates apply. In 2026:

Source: IRC § 55(d), inflation-adjusted per IRS Rev. Proc. 2025-32.

The phase-out works at 25 cents per dollar of AMT income above the threshold. For a single filer with AMT income of $826,350 (i.e., $200,000 above the $626,350 phase-out start), the exemption shrinks by $50,000 — from $137,000 to $87,000. By $1,174,000 of AMT income, the exemption is gone entirely and every dollar is taxed at AMT rates.

AMT tax rates: 26% on the first $248,300 of AMT taxable income (income above the exemption), then 28% on everything above that. These rates are lower than the top regular rate of 37%, but they apply to a much broader income base — because AMT income includes the ISO spread that regular tax ignores.

Worked example: $150K W-2 income + $300K ISO spread (single filer)

A San Francisco software engineer earns $150,000 in W-2 salary. In January 2026, she exercises 10,000 ISOs with an exercise price of $10 and a fair market value of $40. The spread: $30 × 10,000 = $300,000. She holds the shares (no sale).

Step 1: Regular tax calculation

W-2 income: $150,000. Standard deduction (single, 2026): $15,750. Taxable income: $134,250. Federal tax using 2026 brackets: approximately $24,490. The ISO exercise is invisible to regular tax — she owes nothing additional.

Step 2: AMT calculation

AMT on $313,000: 26% on the first $248,300 = $64,558, plus 28% on the remaining $64,700 = $18,116. Tentative minimum tax: $82,674.

AMT owed = tentative minimum tax − regular tax = $82,674 − $24,490 = $58,184.

She owes $58,184 in AMT on top of her regular tax — a total federal bill of roughly $82,674 — on shares she hasn’t sold.

The cash problem: that $58,184 is due by April 15, 2027 (or via quarterly estimated payments starting Q1 2026). She hasn’t sold a single share. If the stock drops 40% between exercise and tax day, her shares are now worth $240,000 — and she still owes $58,184 in AMT on the original $300,000 spread.

Where AMT bites hardest: the income range that matters

AMT doesn’t hit evenly across all income levels. It hits hardest in a specific band:

The pattern: AMT bites hardest when the ISO spread pushes you well above the exemption but your regular tax rate is still in the 22%–24% bracket range. Once your regular income alone puts you in the 35%–37% bracket, regular tax often exceeds tentative minimum tax anyway, and AMT may not apply at all — or applies to a smaller increment.

The danger zone for 2026: single filers with $100K–$250K W-2 income exercising $150K+ of ISO spread. That’s the sweet spot where regular tax is moderate, AMT income is high, and the gap between the two systems is widest.

The AMT credit: how you get your money back (eventually)

The AMT you pay on ISO exercises isn’t permanently lost. Under IRC § 53, it generates a minimum tax credit (MTC) that carries forward indefinitely. In any future year where your regular tax exceeds your tentative minimum tax, you can use the MTC to reduce your regular tax — dollar for dollar — down to the tentative minimum tax floor.

How recovery works:

1. Year 1 (exercise year): you pay $58,184 in AMT. This becomes your MTC balance.
2. Year 2: regular tax is $35,000, tentative minimum tax is $28,000. You can use $7,000 of MTC. Remaining MTC: $51,184.
3. Year 3: regular tax is $40,000, TMT is $25,000. Use $15,000 of MTC. Remaining: $36,184.
4. Continue until MTC is fully recovered.

The problem: recovery is slow. If you’re a consistent W-2 earner in the same bracket, the gap between regular tax and TMT may only be $5K–$15K per year. At that rate, recovering a $58,000 MTC takes 4–7+ years. You’re effectively giving the IRS an interest-free loan for the duration.

When recovery accelerates: the year you actually sell the ISO shares. If you sell at a gain, regular tax jumps (recognizing the gain as LTCG), while AMT income doesn’t change much (it already included the spread at exercise). That year, regular tax often far exceeds TMT, and you can claim a large chunk — or all — of the remaining MTC.

Same-day sale vs. disqualifying disposition: eliminating AMT entirely

The single most effective AMT avoidance strategy for ISOs is also the simplest: don’t hold the shares.

Same-day sale (exercise and sell immediately)

Exercise your ISOs and sell the shares on the same day. This is a disqualifying disposition under IRC § 422(a) because you haven’t held the shares for 1 year from exercise and 2 years from grant. The tax consequence:

• The spread ($300,000 in our example) is taxed as ordinary income on your W-2
• It is not an AMT preference item — AMT exposure is zero
• You owe regular income tax at your marginal rate (likely 24%–35% federal, depending on total income)

The math on $300K spread, same-day sale (single, $150K W-2):

The trade-off is clear: a qualifying disposition saves roughly $12,600 in total federal tax ($84,000 − $71,400) — but it requires fronting $58,184 in AMT, holding concentrated stock for 1–2 years, and accepting the risk that the stock drops below your exercise price. The same-day sale costs more tax but produces immediate cash, zero AMT, and zero stock risk.

For most tech employees — especially those where ISOs represent a significant fraction of net worth — the same-day sale is the concentration-risk-adjusted better outcome. The $12,600 tax savings from holding isn’t worth the risk of a 40% stock decline that turns a $300,000 spread into a $180,000 loss with a $58,184 AMT bill still owed.

Partial exercise: staying below the AMT line

If you want to hold shares for LTCG treatment without triggering massive AMT, the strategy is staged annual exercises. The goal: exercise just enough ISOs each year so the spread, when added to your regular income, keeps AMT taxable income near zero.

For a single filer earning $150,000:

• AMTI before ISOs: ~$165,750 (regular income + standard deduction add-back)
• AMT exemption: $137,000
• AMT taxable income before ISOs: ~$28,750
• Regular tax at $134,250 taxable income: ~$24,490
• TMT at $28,750 AMT taxable income: ~$7,475 (26% rate)
• Regular tax exceeds TMT by ~$17,015 — no AMT owed

You can add ISO spread up to roughly $65,000–$80,000 before TMT catches up to regular tax. Model the exact crossover with your CPA each December before exercising. Exercising $75,000 of spread per year over 4 years avoids almost all AMT while still achieving qualifying disposition treatment on each tranche.

California state AMT: the extra hit no one mentions

California is the state that matters most for ISO AMT because it has the highest concentration of tech employees holding ISOs — and it imposes its own AMT at a flat 7% rate. California conforms to the federal treatment: the ISO exercise spread is a state AMT preference item.

California AMT calculation on our $300K spread example:

If California regular tax on $150,000 income is roughly $8,500 (using CA’s 9.3% bracket at that level), the CA AMT owed is approximately $16,490 ($24,990 − $8,500). Combined with ~$58,184 federal AMT, the total AMT bill is approximately $74,674 — on shares that haven’t been sold.

California does allow an AMT credit carryforward (similar to the federal MTC), but recovery follows the same slow pattern. For California tech employees exercising large ISO grants, the combined federal + state AMT makes the same-day sale even more compelling.

States with no income tax (Texas, Florida, Washington, Nevada, Tennessee, and 4 others) have no state AMT. A Washington-based tech employee exercising the same $300K of ISOs saves the entire ~$16,490 CA AMT hit. This is one reason equity-comp planning differs by state — the hold-vs-sell math is materially different when state AMT is zero.

The post-termination trap: 90 days to decide

When you leave a company — voluntarily or via layoff — your ISO exercise window shrinks to 90 days by default under IRC § 422(a)(2). After 90 days, unexercised ISOs expire worthless. Some companies extend this to 1–10 years in their equity plan, but the extension converts the options from ISOs to non-qualified stock options (NSOs) after the 90-day mark — meaning the spread is taxed as ordinary income at exercise regardless.

The forced decision: a laid-off engineer holding 20,000 ISOs with a $25 spread faces a $500,000 AMT preference item if she exercises within 90 days and holds. If she doesn’t exercise, she loses the options entirely. If she exercises and the stock drops, she’s stuck with AMT on a spread that no longer exists in market value. This is the scenario where a same-day sale (or a carefully sized partial exercise) is usually the right call — especially if severance is also hitting as ordinary income in the same tax year.

ISO vs. NSO: why the AMT problem is ISO-specific

Non-qualified stock options (NSOs/NQSOs) don’t trigger AMT at exercise. The spread on an NSO exercise is taxed as ordinary income on your W-2 immediately — your employer withholds taxes just like a paycheck. The trade-off:

ISOs are favorable when you can hold for a qualifying disposition and the AMT cost is manageable. NSOs are simpler, predictable, and generate no AMT surprise. For employees who receive both, understanding the tax mechanics of each grant type before exercise is the difference between a planned tax bill and a crisis.

Quarterly estimated tax payments: don’t wait until April

If you exercise ISOs early in the year and expect to owe AMT, the IRS expects you to pay via quarterly estimated tax payments (Form 1040-ES). The penalty for underpayment is assessed per quarter. The safe harbors:

• 100% of prior-year tax (110% if prior-year AGI exceeded $150,000) — pay at least this and no penalty applies regardless of current-year liability
• 90% of current-year tax — if your withholding + estimated payments cover 90% of the total 2026 bill, no penalty

For a tech employee whose 2025 tax was $30,000 and whose 2026 tax (including AMT) will be $83,000, the 110% safe harbor means paying at least $33,000 in estimated + withheld taxes. That’s likely already covered by W-2 withholding. But if your 2025 tax was $80,000 (perhaps you also exercised ISOs last year), the 110% safe harbor is $88,000 — and you may need to make quarterly payments to avoid penalties.

Planning framework: the 4 questions before every ISO exercise

1. What’s my AMT exposure? Model the spread × shares against the 2026 exemption ($137K single / $220.7K MFJ). If AMTI stays under the exemption, exercise freely. If it pushes above, size the exercise accordingly.
2. Can I fund the AMT bill without selling shares? If you need to sell shares to pay AMT, you’re defeating the purpose of holding for LTCG treatment. If you can’t fund it from savings, a same-day sale on some or all shares is the disciplined move.
3. What’s my concentration risk? Post-exercise, what percentage of your net worth is in a single company’s stock? If it’s above 10–15%, the LTCG savings from holding are unlikely to justify the concentration risk. The math on concentration risk applies to ISOs exactly as it does to RSUs.
4. What’s my state AMT exposure? California adds 7% state AMT. Texas, Florida, and Washington add zero. The state you live in on December 31 of the exercise year determines state AMT liability.

The bottom line

ISOs are the most tax-advantaged form of equity compensation — if you can afford to hold. The AMT preference item under IRC § 56(b)(3) means every dollar of spread at exercise becomes taxable income in a parallel system, even though regular tax ignores it. In 2026, single filers with $100K–$250K W-2 income exercising $150K+ of spread are in the highest-impact zone. The AMT exemption of $137,000 (single) provides a buffer, but a $300,000 spread blows through it easily and produces a $58,000+ federal AMT bill on paper gains. California adds another $16,000+. The AMT credit lets you recover this over 3–7 years, but you’re fronting the cash now on shares you haven’t sold. For most tech employees, staged annual exercises targeting the AMT exemption — or a same-day sale when the numbers are large — is the approach that controls both tax and concentration risk. The worst outcome isn’t paying AMT. It’s paying AMT on shares that later drop below your exercise price.