To cease the child support payments, you will need to contact the child support division in the County Clerk's office wherein you receive the payment. Your ex should contact the division and advise you child is now of legal age.

As long as neither of you report to the child support services or file a petition with the court then child supportwill continue. You should first contact the child support services, in some states you have to file a pettion with the court to have the order stopped, the child support services will advise you on this if needed. Also you need to keep the child support and not spend it, if you spend it you may have to pay it back to the father.

If he is on any assistance from the state (the child) you have to drop that and then go to enforcement and file a motion to stop the case/support. Its real easy not that hard but if he owed you back support thats what your gettin now. If not just go stop it! The father cant do it its all up to you

I did not get in your question that you were stating that the father owed any back erarages, so if he does not then you do need to contact the child support services and report the child is of age, if the father owes any back erarages then of course the child support service will continue to collect, but even if this were to be the case the child support for all current child support payments still need to be stopped, so that the father would not be paying a current amount and any payments on back erarages. So contact the child support services and still report the child is of age.