Assuming that your divorce was official prior to tax year 2019, the alimony paid would be entered on the 2018 tax return as an Adjustment to income on Schedule 1 Line 31a. The totals from Schedule 1 Line 36 are subtracted from your Total Income reported on Form 1040 Line 6 and entered on Form 1040 Line 7 as Adjusted gross income.
Your tax liability is based on your Adjusted Gross Income not your Total Income after subtracting the Standard or Itemized Deduction from the AGI.
