dependents and taxes

michigan
I am divorced with one child that I have custody of. Part of the divorce agreement is that my ex gets to claim my child every year as a dependent on his taxes. After 4 years I find out that he has also been claiming the child care credit and the head of household. I have been doing the same. I far as I knew I was the one that could do that since he lives with me. Am I wrong? Is this fixable? Will I get an audit?
HELP!

If you pay more than half the cost of keeping up your household, you qualify for head of household. You are entitled to the status because your unmarried child lives with you, and that is the case even if you are not eligible for the exemption.

If your ex has the right to claim the exemption under the divorce decree with no conditions, such as the payment of support, then he is entitled to the Child Care Credit. If the payment of support is a condition of his taking the exemption, then you are entitled to that credit. For all the rules relating to the credit, see Chapter 33, Child and Dependent Care Credit of IRS Publication 17, Your Federal Income Tax, which you can download for free at the IRS site at: http://www.irs.ustreas.gov/forms_pubs/index.html