Why the bargain element matters
When you exercise ISOs and hold the shares (don't sell same-day), the IRS treats the spread between the fair market value at exercise and your strike price as AMT preference income on Form 6251. That preference gets added to regular taxable income to compute AMTI. AMTI runs through a parallel rate schedule (26% up to $239,100, 28% above) with its own exemption and phase-out. You pay the larger of regular tax and tentative minimum tax.
Illinois's role
Illinois does not calculate a separate state AMT. The only AMT layer is federal. State tax still applies to any ordinary income recognized from a disqualifying disposition in the same year.
The AMT credit
AMT paid on an ISO exercise creates a minimum tax credit under IRC §53 that carries forward indefinitely. In future years where regular tax exceeds tentative minimum tax, the credit absorbs the excess. Recovery takes time. For a typical high-income filer, $568,755 of federal AMT recovers over roughly 12 years, faster when you eventually sell the ISO shares.
Frequently asked
- What is the AMT on a $2,000,000 ISO exercise in Illinois?
- Approximately $568,755 total. Federal AMT is about $568,755. Illinois does not levy a separate state AMT, so state tax on an exercise-and-hold is zero in the exercise year.
- Does Illinois have its own AMT on top of federal?
- No. Illinois does not have a separate state AMT. Only federal AMT applies on an exercise-and-hold. If you sell the ISO shares in a disqualifying disposition, state ordinary tax applies to the spread recognized as wages.
- How do I avoid this AMT bill?
- Three options. Exercise smaller amounts each year to stay under the AMT trigger point. Do a same-day-sale (cashless exercise), which creates a disqualifying disposition and eliminates the AMT preference at the cost of converting long-term gain into ordinary income. Or pay the AMT and claim the credit on Form 8801 in future years when regular tax exceeds tentative minimum tax.
- When does the AMT credit come back?
- The minimum tax credit under IRC §53 carries forward indefinitely and offsets regular tax in any future year where regular tax exceeds tentative minimum tax. For a typical high-income filer, a $568,755 federal AMT credit recovers over roughly 12 years at $40-60k per year.
Related
- ISO AMT calculator (customize with your own numbers)
- AMT credit recovery calculator
- Illinois ISO AMT overview
- Complete ISO guide
Educational estimate · 2025 federal AMT · Single filer · $250k other wages · Not tax advice