In Kansas its to age 18 or when the child graduates from HS whichever is later except that if the obligee has held back the child in school which makes him/her graduate at the age of 19, and the obligor was not involved in the decision, then it ends at 18.
Those rules are getting rarer and rarer. Most moms know that if they can get their children on ADHD meds and labeled as “special needs” aka for the most part “lack of discipline,” they can collect CS well beyond 18 and past the age of 21. Therefore the “child” takes continual remedial grade school/high school non-acredited college courses well past 19 and can continue to collect CS and college funds from dear old dad. The community colleges in particular, LOVE this cash cow, by the way.