The below Michigan Statute states the Court has authority to backdate a child support modification based on the "date that notice of the petition was given" to the payer or payee. This means to file a motion right away and document proof of service if support should be modified based on a difference in income, unemployment, change to the parenting schedule, etc. The motion hearing may be dismissed with entry of a consent order if an agreement is reached together. If not, the Court will decide the issues and will be able to backdate the request for support modification to the date notice of the motion was provided to the opposing party.
MCL 552.603 Support order; enforcement; information to be included; notice of new information; service of notices or other papers; accrued interest prohibited; failure to comply with requirements; fee; admission into evidence.
(1) A support order issued by a court of this state shall be enforced as provided in this act.
(2) Except as otherwise provided in this section, a support order that is part of a judgment or is an order in a domestic relations matter is a judgment on and after the date the support amount is due as prescribed in section 5c, with the full force, effect, and attributes of a judgment of this state, and is not, on and after the date it is due, subject to retroactive modification. No additional action is necessary to reduce support to a final judgment. Retroactive modification of a support payment due under a support order is permissible with respect to a period during which there is pending a petition for modification, but only from the date that notice of the petition was given to the payer or recipient of support.
(3) This section does not apply to an ex parte interim support order or a temporary support order entered under supreme court rule.
(4) The office of the friend of the court shall make available to a payer or payee the forms and instructions described in section 5 of the friend of the court act, MCL 552.505.
(5) This section does not prohibit a court approved agreement between the parties to retroactively modify a support order. This section does not limit other enforcement remedies available under this or another act.