For my clients, I always set up a process in the Settlement Agreement or Child Support Order to deal with this. The party with insurance coverage will bear the initial burden of the first $100 per child per year (per the statute) along with co-pays and deductibles. Then, we require the parent who incurs a bill to send it to the other parent within a specified period of time. This is negotiable, but I typically require submission within 30 days.
There has to be a time period in which a party can object to a bill on the basis that it is not reasonably necessary or was simply not incurred. If the parties cannot agree after an objection is made, the party incurring the bill will need to file a motion to bring the dispute before the court. If there is no objection, reimbursement should be required within the same 30 day period of time.
Even without a gameplan in place, the law requires the allocation. As a judge, I saw many a parent bring in a stack of the last 5 years of bills and expect the other to pay his or her share within a couple of weeks. With no plan in place, it seems the judge is justified in drawing the line somewhere – 6 months, or a year, whatever – and applying the equitable doctrine of laches to cut off collection efforts. ("Laches" is a technical legal principle that is beyond the scope of this Lesson.)
Now you have some idea about how to deal with extraordinary medical expenses, so unless you choose to worry about the doctrine of laches, have a great day!