My ex has custody of our son. She won't allow me to claim him on my taxes. Instead, she let's her parents claim him because she says they'd get more back than she would. My ex & our son live in their own home on her parents' property. Since my ex recieves social security and works part-time (this is what she tells me) and doesn't even live in the same house as her parents, can her parents claim my son on their taxes?