The question is not clear whether if you wanted to declare child support payments made or declare child support payments received. As per turbotax, you may enter the child support payment made in line 230 of your return. As for line 220, you would enter the amount that is deductible (it could be a portion of the total annual payments or the total). Please note that Child support arrangements made in April 1997 or later are not deductible.
On the other hand, you may enter the total of all received support payments on line 156, and declare the taxable amount on line 128 of your return. If the child support payments received was before or on April 1997 then you would enter the same amount on line 128 as the amount you entered in line 156. However, if the child support payments received on after or May 1997, child support are not declared as taxable income and are subtracted from the amount in line 156 to give your line 128 amount.
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