How can I find out how much child support I paid out in 2018??

[DoninGA]

Only you would have that information.  However you pay the support is where you should look to see the total amount.

[xmasbaby0]

Child support is not entered on a tax return, so you have no way to get that information here.  Check through your own bank records or check whatever other method is being used to get your support payments--employer garnishment, etc.  Or ask the other parent--they probably know.

[Carl]

Also, child support is not deductible on your federal tax return anyway.