I have been paying child support thru the court system, My youngest is 21

Q) I have been paying child support thru the court system of Massachusetts. My youngest is 21 and not in school. My oldest is 23, working, has a baby and this will be her 5th year in college. Both are still living with their mom in Virginia. How long am I obligated to pay support?

A) In Massachusetts, child support typically ends when the child reaches the age of 18, or 23 if they are still in college full-time. However, since your children live in Virginia, you should check the laws in that state as they may differ from Massachusetts. It is also possible that the terms of your child support agreement or court order specify a different age or circumstance when child support ends. You should consult with an attorney or contact the child support agency in Virginia to determine your specific obligations.

NOTE: In in Massachusetts the court has the discretion to continue to award child support after age 18 and up to age 23 so long as your child is attending school full time and is principally dependent upon that parent for support. You may want to seek legal aid and enquirer about how to get a stop order on your current child support requirements if by law you are no longer legally required to pay child support.

Source: http://www.bostondivorcelawyer.com/MA%20Frequently%20Asked%20Questions/Massachusetts%20Child%20Support%20FAQ.html#Does_child_support_continue_aft