What is the IRS definition of an "injured spouse?"?

A person filing a joint tax return whose refund is applied in whole or in part to the spouse's past income tax debt may be considered an injured spouse, according to the IRS. The same applies to refunds that go toward a spouse's child support or student loan debt.

To qualify as an injured spouse, an individual must have paid taxes or claimed a refundable tax credit, such as the earned income credit or additional child tax credit, the IRS states. The injured spouse also cannot be legally obligated to pay the spouse's debt. Special rules apply in community property states.