If mom was ordered by the custody court to provide insurance for the child, dad can take her back to court on a show cause motion, asking that she explain to the court why she allowed the insurance to lapse. He can also seek reimbursement for the portion medical bills that he pays that should have been covered by insurance, had mom not let the insurance lapse. (e.g., if the parents would have had to split a $100 copayment had the insurance been in effect, with a 50/50 split of out-of-pocket medical costs, he should have only been on the hook for $50, so he can ask that the court order the mother to reimburse him for any amount he has to pay in excess of the $50.)

If appropriate, dad could also seek to modify the order such that he is the parent who provides health insurance.