If a child support enforcement agency modifies an administrative child support order, or a court modifies a court child support order, based on an administrative review conducted pursuant to section 3119.771 of the Revised Code, the modification shall relate back to the later of the date the child support enforcement agency sent notice of the review pursuant to division (A) of section 3119.771 of the Revised Code or the first day of the month in which the obligor‘s active military service begins. The agency or court shall include a provision in the modified order stating that, except as otherwise provided in division (C) of section 3119.771 of the Revised Code, the modification will terminate and the prior amount of support be reinstated as of the first day of the month following the date that the obligor’s active military service ends.