No. Paying child support is not entered on a tax return and if he lives with the other parent she can claim him as a dependent. He cannot be claimed on two tax returns. IF there is a signed agreement between you and the other parent there is a way for you to claim him but only if you have a signed Form 8332 that allows you to claim him for the child tax credit and the custodial parent to file as Head of Household, and get earned income credit. Do you have a signed form 8332?