Under pre-Act law, higher-income taxpayers who itemized their deductions were subject to a limitation on these deductions (commonly known as the “Pease limitation”). For taxpayers who exceed the threshold, the otherwise allowable amount of itemized deductions was reduced by 3% of the amount of the taxpayers' adjusted gross income exceeding the threshold. The total reduction couldn't be greater than 80% of all itemized deductions, and certain itemized deductions were exempt from the Pease limitation.

New law. For tax years beginning after Dec. 31, 2017 and before Jan. 1, 2026, the “Pease limitation” on itemized deductions is suspended.