do u have to pay chil support for a child if not in school

Yes. Just because a child does not go to school,does not mean his custodial parent does not get child support. You must pay child support until the "child" is 21, unless the child is emancipated. The test for emancipation is a financial test. The question is whether the child is financially independent, for example, if he lives on his own, pays his own insurance and has a job.