The payment or receipt of child support does not affect your taxable income. You should not report child support payments in your income.
If you make child support payments, you cannot deduct the amount you paid. If you receive child support payments, the amount you receive is not taxed. Do not report this amount on IRS Form 1040, Line 21 Other Income.
Child support is defined as payment that is specifically designated as child support or treated as specifically designated as child support under your divorce or separation instrument. The amount of child support may vary over time.