I am helping my uncle prepare his taxes. He has a 16 year old boy that lives with gramma and dad. During the school year he went home to grammas after school, and then to dads for the late afternoon and night, and during the summer evenly spent time with both, pretty much an even 6 months with each. Gramma wants to claim him because she runs a business, and takes him to a large amounts of doctors appointments and gets him on tons of medications with no medical insurance, and if she claims him she gets more deductions. (i personally think if she wants it all for him, she should have to take the fall for the money she decides to spend on it but oh well) Whereas now he mainly lives with his dad, but during 2008, he was 6months with dad 6 months with gramma. The rules say that you can claim a child that has lived with you for over 6 months, so what about a child that lives with both for 6 months each? who gets to claim?