(a) The amount of the monthly Social Security benefits or apportioned veterans’ benefits provided for a joint child shall be included in the gross income of the parent on whose eligibility the benefits are based.

(b) The amount of the monthly survivors’ and dependents’ educational assistance provided for a joint child shall be included in the gross income of the parent on whose eligibility the benefits are based.

(c) If Social Security or apportioned veterans’ benefits are provided for a joint child based on the eligibility of the obligor, and are received by the obligee as a representative payee for the child or by the child attending school, then the amount of the benefits shall also be subtracted from the obligor’s net child support obligation as calculated pursuant to section 518A.34.

(d) If the survivors’ and dependents’ educational assistance is provided for a joint child based on the eligibility of the obligor, and is received by the obligee as a representative payee for the child or by the child attending school, then the amount of the assistance shall also be subtracted from the obligor’s net child support obligation as calculated under section 518A.34.

(e) Upon a motion to modify child support, any regular or lump sum payment of Social Security or apportioned veterans’ benefit received by the obligee for the benefit of the joint child based upon the obligor’s disability prior to filing the motion to modify may be used to satisfy arrears that remain due for the period of time for which the benefit was received. This paragraph applies only if the derivative benefit was not considered in the guidelines calculation of the previous child support order.