A friend of mine has had custody of his son for two years and each tax year he tries to claim son it says the mother already has. How does he fix this and can he get refunded?

What does it say in the custody paperwork about this? Usually there is something stated as to who gets to take the child as a dependent on their taxes. If it says the father gets the deduction and the mother has already taken the deduction against his wishes - then the father can contact the IRS and show them a copy of the custody paperwork showing he gets the deduction instead of the mother. They will honor the custody paperwork and take the deduction money the mother was given through her tax refund back. Check the paperwork first and ask father why mother is taking the deduction contrary to what the paperwork says.

Take a look at Pub 501 - specifically page 11: http://www.irs.gov/pub/irs-pdf/p501.pdf

It states that the parent who has custody will almost always have the right to claim the child. The custodial parent is the one with whom the child spent a greater period during the year. So unless there is a divorce decree that states otherwise, it seems that the father in this case has the right to claim the child.

Your friend should file his taxes and include the child as a dependent. He will most likely not be able to do this via e-file if the mother has already beaten him to it - the computer system will note the discrepancy and automatically reject it. So he will have to send in a paper return, and he should include a statement with his return that says he is claiming the exemption for the child because he is the custodial parent. The IRS will see the conflict with the mother's tax return, and investigate.