California AMT 2026 State Alternative Minimum Tax Calculator

California AMT 2026 is the state-level Alternative Minimum Tax imposed at 7% on Alternative Minimum Taxable Income with a $93,719 single / $124,959 joint exemption (phased out at AMTI of $312,397 single / $416,529 joint). It is computed on Schedule P (540) for residents and is separate from federal AMT — California still imposes it even though TCJA largely neutralized federal AMT.

Why California AMT Still Matters in 2026

Federal AMT became rare after TCJA raised exemptions and capped state tax deductions. But California did not conform — the FTB kept its own 7% AMT with much lower exemptions, so high-income Californians who escape federal AMT still owe state AMT. The most common triggers are ISO bargain element (incentive stock options exercised and held past year-end), depreciation timing differences, and passive activity loss limitations. Silicon Valley engineers exercising ISOs are the textbook CA AMT victims.

Schedule P (540) Computation Flow

Start with federal AMTI (Form 6251 line 4), then make CA-specific adjustments: add CA depreciation differences, add back ISO bargain element if CA-sourced, subtract items that are federal preferences but not CA preferences (e.g., post-1986 depreciation differences California chose not to conform). Apply the $93,719/$124,959 exemption with 25% phase-out, then 7% on the excess. Subtract regular CA tax (Form 540 line 31); positive remainder is California AMT entered on Form 540 line 61.

Planning Around California AMT

(1) Time ISO exercises — if you exercise and hold, the bargain element is a CA AMT preference; consider same-year sales (disqualifying disposition) to avoid AMT exposure. (2) CA AMT credit carryforward — like federal, AMT paid on deferral items (depreciation, ISO) generates a credit recoverable in future years on FTB Form 3510. (3) Move state residency carefully — partial-year residents prorate AMT by CA-source income. (4) Tax-free interest — California also has its own private activity bond add-back rules; double-check before investing.

Last updated May 2026. Sources: California FTB Schedule P (540) Instructions, FTB Form 3510 (AMT Credit).

The California AMT Credit: Getting the Tax Back in Later Years

Paying California AMT in one year is often not the end of the story. Where the AMT arises from timing differences — most commonly exercising incentive stock options and holding the shares across a year end — California allows a credit against regular tax in later years, so the extra tax paid now can come back when regular tax exceeds tentative minimum tax. Two rules decide whether you actually recover it. First, the credit only offsets the amount by which regular tax exceeds tentative minimum tax in the later year, so a year with high preference items recovers nothing and the credit simply carries forward. Second, the credit must be tracked and claimed on the return each year; it is not applied automatically, and a missed year means recomputing the carryforward rather than losing it outright. Keep the Schedule P (540) computation and your option exercise records together, because the cost basis used for the AMT calculation differs from the regular tax basis and you will need both when the shares are eventually sold. Forms, instructions and the current Schedule P are published by the California Franchise Tax Board.

What Usually Triggers California AMT: Incentive Stock Options

Most people who owe California AMT never planned for it, and the usual cause is exercising incentive stock options and holding the shares. For regular tax the bargain element — the gap between the strike price and the fair market value on the day you exercise — is not income. For AMT it is, immediately, in the year you exercise, even though you have sold nothing and received no cash. That is how an engineer at a private company ends up with a large California tax bill and no liquidity to pay it. Other common preferences and adjustments include depreciation timing differences, certain passive-activity losses, and income from private-activity municipal bonds. The defence is timing rather than avoidance: exercising fewer shares per calendar year, or exercising and selling in the same year so the gain is taxed as ordinary income instead of creating an AMT preference. Model the exercise before you sign, not in April. Source: California Franchise Tax Board — Schedule P (540) instructions. Updated 2026-09-18.

The California AMT Credit: Getting the Money Back Later

California AMT paid because of a timing difference is not lost — it generates a minimum tax credit you carry forward and use in later years when your regular California tax exceeds your tentative minimum tax. The classic case is the ISO exercise: you pay AMT in the exercise year, then recover it across the years after you sell the shares, because the shares carry a higher AMT basis than regular-tax basis and that difference reverses. The distinction that decides whether you ever see the money again is timing versus permanent. Deferral items such as depreciation and ISO bargain elements generate the credit; exclusion items generally do not. The credit is non-refundable, so it only ever offsets a real California tax liability, and it can sit unused for years if your income stays flat. Track it every year on Schedule P — taxpayers routinely forget the carryforward exists and leave it stranded. Source: California Franchise Tax Board. Updated 2026-09-18.