Depends on what the divorce decree says as to who can claim the child. if nothing in divorce decree, I would check with the grandparents and just say you are going to claim him this year on taxes and get something in writing. if both of you claim it will be a big problem at some point down the road. You also might want to talk with your divorce attorney about this.
Read IRS Publication 501 to make sure you qualify to take the deduction. It is best to have an agreement in writing with your spouse allocating the exemption to you. Without a written agreement there is a chance that the grandparents might also try to claim it which could prove a problem with the IRS.
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