The Prior-Year Minimum Tax Credit lets you get back money you paid as an AMT in a prior year. You can only claim this credit in a year when you don't have to pay AMT. You can't use the credit to reduce your AMT liability in the future.
Individuals, estates, and trusts use this form to figure:
The minimum tax credit, if any, for alternative minimum tax (AMT) they incurred in prior tax years.
Any credit carryforward to next year.
Form 8801PDF
Instructions for Form 8801 (Print VersionPDF)