I am wondering if I should let my ex husband claim our child on his tax return for 2014? I saw somewhere that I could waive my right to claim our son as a dependent even though he lived with me 11 months out of the year. Last year I received all of my ex husbands (small) tax refund as he has child support arrears. So, I am wondering if this would be advantageous since I am not using the credit due to not earning much (under $3000) and on disability and he would then likely get a much higher refund ( to once again, pay off his large arrears)

Also, I was not eligible for EIC or CTC as did not earn enough last year and perhaps the year before that - can my ex go back and claim him for those years even if he already filed for those years?