Can I file head of house hold, and keep my refund, when my husband owes back taxes?

My husband and I just got married in August. He is a subcontractor and hasn't worked since the summer. My 5 yr old stepson lives with us, but we are not the custodial parents. My husband owes back child support AND back taxes that were from before we were married. So...I have provided over half of the income to run my household for the whole year and I want to be able to claim my stepson, and file head of household when I file my taxes. My question is can I legally do this, and will my refund go toward my husbands debts?