Age limit for students

by Jonathan
(Albany,New York)

My oldest son just turned 21. He lives on college campus & has been for 3 yrs now. He spends some time @ home when on vacation otherwise he lives on campus.He also holds a part-time paying job tutoring @ the college.I stopped sending child support for him & continued sending support for my 17yr old son (using the state chart). My Ex. insists I should still be sending child support for our 21 yr old son even though he doesn't live @ home until he's 23 because he's a full time student.Our divorce agreement says when he's 21 & that's it.Which way is correct by law ?