9 CAR § 5-103
(a)
(1) Past due child support, also known as arrears:
(3)
(4) The caseworker shall make a diligent effort to:
(c) Interest.
(2) If interest is reduced to a judgment by the court or the amount of interest owed is received as a sum certain from another state, the office will:
(4)
(i) Reasonable based on the information provided for the calculation; and
(ii) Calculated in accordance with state law pertaining to child support interest.
(C) Documentation supporting the calculation must be attached in order for the office to include the interest amount as a child support debt.
(2) Advance notice must be provided to the noncustodial parent regarding the delinquency of the support payment and the requirements for posting the: