Child support is not normally shown on your W-2, and you do not add it to your W-2. If the child support is being taken out of your pay, it's possible that your employer would show it somewhere on your W-2. There is no box for child support on a W-2, but they could possibly put it in box 14, or in an unused space on the form. In any case, it's just for your information. It doesn't go on your tax return.
