Can my ex-wife cancel past due support? Can child services make me pay the arrears even when I'm not working?

No matter what your ex wife tells you, there is only one way to cancel or modify support, and that is in court.  YOU CANNOT RELY ON SUCH PROMISES, EVEN IF GENUINE AT THE TIME. THEY HAVE NO LEGAL EFFECT. If you have a DCSS support order, you need to go to DCSS in your county and explain the circumstances to a case worker.  If your wife agrees, you can make a written agreement signed by the court (a stipulation and order) through that agency to suspend or reduce support or modify arrears.  Otherwise, you need to file a motion.