If you are talking about past due support, that goes to the mother. After 18, if she stays in school, the "child" gets the current support. If support is modified, BOTH parents will be required to pay support to her until age 21 so long as she stays in school.
Be sure to designate "best answer." If you live in Oregon, you may call me for more detailed advice, 503-650-9662. Please be aware that each answer on this website is based upon the facts, or lack thereof, provided in the question. To be sure you get complete and comprehensive answers, based upon the totality of your situation, contact a local attorney who specializes in the area of law that involves your legal problem. Diane L. Gruber has been practicing law in Oregon for 26 years, specializing in family law, bankruptcy, estate planning and probate. Note: Diane L. Gruber does not represent you until a written fee agreement has been signed by you and Diane L. Gruber, and the fee listed in the agreement has been paid.
Assuming that a child support payment was due every month on the first of the month, each monthly payment that was not made becomes a judgment in favor of the parent who was not paid and against the parent who failed to pay. Those judgments do not go away just because a parent who had been ordered to pay child support is no longer obligated to make any additional child support payments. So, a parent who failed to make all of the child support payments that parent was obligated to make in the past is still obligated to pay that unpaid child support regardless of what the child does or does not do after the child turns 18. There is a statute of limitations for unpaid child support obligations, so a parent who is owed child support does not have an unlimited amount of time to try and collect it. I would encourage each parent to seek independent legal counsel with experience in Oregon domestic relations law to determine what options may be available to each of them in dealing with this situation
Child support judgments are monthly. Every month a payment is due, that payment amount is a separate judgment. Child support judgments are good for 25 years. Simple interest is calculated at 9% per annum on each monthly child support payment that is unpaid. When a payment is made, it is made against arrearages and interest before being applied to any current support due. Since the current judgment creditor is the child's mother, she is the one to whom child support is owed. If the child does not go to college, her mother still has a right to collect for some time until she is paid in full. Child support arrearages and interest can be calculated and put into a separate judgment that allows the parent entitled to the child support to use various means to collect, including garnishment, liens and the like. It is also legal to collect interest on the interest calculated as part of the judgment for arrearages. When the child reaches 18 years of age, she is a mandatory party to the child support case. The statutes say that she is entitled to be paid directly by both parents at that point, so long as she qualifies as a child attending school. However, there are rebuttal factors that can operate to allow her mother to be paid if, for instance, the child is living at home and going to school. It could be to your wife's benefit to calculate the interest due her as well as the back child support and have a judgment entered against the father. Thereafter, if her daughter attends school, she and her daughter can decide how they want to handle child support. Regardless, it would be in your wife's best interest to talk to an attorney if, in fact, the back support can be collected from your step-daughter's father. However, a great deal depends on the facts of your case. If your step-daughter's father is judgment proof, then you might be wasting your time and money.