The responsible parent's net medical debt is the difference between the total medical debt and the amount for which the responsible parent is entitled to receive credit. In order to receive credit, the responsible parent must document that he or his insurer has paid all or part of the qualified medical expenses that comprise the total medical debt. Credit is limited to the actual amount paid.
If any such asset is owned jointly by the responsible parent and the custodial parent, the credit for such payments may not exceed a percentage equal to the custodial parent's percentage share of ownership, title, or equity of or in the asset. Such payments, with respect to real property, can qualify for credit only with respect to the residence in which the custodial parent and the dependent child(ren) are actually living. The only other asset for which a payment made by the noncustodial parent qualifies for credit is payment on/for a motor vehicle in operating condition and in the possession of the custodial parent.
10- 144 C.M.R. ch. 351, § 8-9