I was wondering if anyone can tell me when child support stops in New York

Depends on the court order and state laws. Some states, it ends when the child turns 18; other states require the non-custodial parent to continue to pay support if the child is attending college and living with the custodial parent.

Either way, any back support still has to be paid - the board doesn't get washed clean once the child is a legal adult.

If this is a newer case the child support runs usually until 21. If its an older case then check your paperwork to see when it ends. NY and Indiana have been running child support till 21.

You need to read the terms of your child support order, it should be spectif