My son turned 19 in October 2016, moved in with me full time last year. His dad claimed him through 2015. I would like to claim him now.Do I need a release from his dad?

If your son lived with you all of 2016, you don't need a release from the dad because you were the custodial parent who has control over the dependency exemption and all other child tax benefits. If your son was not a full time student in 2016 for at least 1 day of 5 different months, you can't claim him as a qualifying child dependent. A child who is not a full time student must be under age 19 at year end to be claimed as a qualifying child.

If you can't claim him as a qualifying child, you may be able to claim him as a qualifying relative dependent if he made less than $4050 and you paid more than half his support for the year.