I live in New York State, married August 2010 new husband may owe back child support. I am filing MFJ claiming him and my (not his) daughter. He has NO income to claim for 2010, zilch... I am filing injured spouse form 8379 just in case there is a child support obligation owed. Wages are all mine, claiming my daughter, so is he entitled to any refund to be offset for child support? If so, how much will they take or how is it determined how much will be offset for his part. Especially when he has no contribution at all.

The Injured Spouse filing will allocate the refund based on the information you provide.

Part of the refund IS his, because filing jointly lowers your tax rate and adds to both the standard deduction and adds an additional (his) personal exemption. However, the Child Tax Credit should be all yours.