will result in an increase in revenues to the Treasury (relative to the revenues that the Secretary estimates would have been received in the Treasury if the applicable percentage were 21 percent) equal to the reduction in revenues to the Treasury which the Secretary estimates will occur by reason of the amendment made by section 2 of the Save the State and Local Tax Deduction for Middle Class Families Act of 2019 . . (b) Effective date The amendment made by this section shall apply to taxable years beginning after December 31, 2018.