When Child Support Ends Under Wisconsin law, a parent's duty to support his or her child continues until the child turns 18, or age 19 if the child is still enrolled in high school or working on a high school equivalency course (GED). If past-due support is owed, the child support case is still enforceable. Notices Sent to Parents Emancipation Notices will be sent to both parents 90 days before the verified date of the 18th birthday of their youngest child. The order for current support will end when the youngest child turns 18 unless a parent shows proof to the child support agency that the child is still attending high school or is enrolled in a program to obtain his or her GED. If your child is going to be 18 soon and you have not received a notice in the mail, you should contact your Local Child Support Agency to ensure that your address is up to date. When Past-Due Support is Still Owed If past-due support is owed when current support ends, the child support will continue to be enforced and collected. Income withholding may continue at the same level of collection until past-due child support is paid in full. Cases with past-due support may be enforced up to 20 years after the youngest child reaches the age of 18.