An entity that paid the AMT received a tax credit (AMT credit carryforward) for the tax paid in excess of the amount owed under the regular tax system. This AMT credit carryforward has no expiration date.

How many years can you carry forward AMT credit?

Any general business credit not allowed generally may be carried back 2 years and carried forward 20 years.

What happens to AMT credit carryforward?

Any AMT credit carryforwards that do not reduce regular taxes generally are eligible for a 50% refund in 2018 through 2020 and a 100% refund in 2021. This generally will result in the full realization of any AMT credit carryforwards existing at December 31, 2017, irrespective of future taxable income.