Child Support – Past Support vs Arrears and How to Calculate

2026 CLE Handout: How to Calculate Back Child Support:

Defining and Differentiating the Terms

Arrears are defined by Minn. Stat. § 518A.26, Subd. 3 which states:
Arrears are amounts that accrue pursuant to an obligor’s failure to comply with a support order. Past support and pregnancy and confinement expenses contained in a support order are arrears if the court order does not contain repayment terms. Arrears also arise by the obligor’s failure to comply with the terms of a court order for repayment of past support or pregnancy and confinement expenses. An obligor’s failure to comply
with the terms for repayment of amounts owed for past support or pregnancy and confinement turns the entire amount owed into arrears.

Past Support also known as back support or retroactive support is not as clearly defined by statute. A practitioner needs to look to case law as well as Minn. Stat. § 518A.82 to learn about the issue of past support. Past support is generally understood to be support which accrues prior to the effective date of the first order for an ongoing support obligation. In custody and support actions, there may be a past support
obligation for up to two years prior to the commencement of the action based upon Minn. Stat. § 518A.82. In a dissolution case there may be a past support obligation going back to the commencement of the dissolution or the date of separation based upon case law discussed below.

• Labelling retroactive or past child support as arrears, when it is not, can be the basis for a reversal on appeal.
• Past support should not be labeled as arrears.
• Use of the label “arrears” can trigger enforcement remedies that can create a hardship for an obligor who has not yet had the opportunity to pay his past support obligation.
• Past due child support should only be labeled as arrears when the obligor has disobeyed a prior order to pay their monthly child support obligation or when they have not complied with repayment terms for past support in a prior order.

General Considerations

• Make sure to plead (request) the issue of past support.
• The award of past support is very discretionary with the court.
• The language of the statute is permissive.
  • “May” is permissive. Minn. Stat. § 645.44, Subd. 15.
• Further, the case law supports the court’s discretion regarding the amount and award of past support.
• These factors can result in variation between past support awards in different cases.
• This discretion provides an opportunity for a practitioner to advocate for their client’s position.
  • Practitioners for an obligee should consider providing evidence regarding the expenses that the obligee solely paid, and what the financial repercussions were of the client having to solely support the joint children.
  • Practitioners for an obligor should consider providing evidence regarding voluntary payments made by the obligor, information about their financial situation which might have impacted their ability to pay in the past, and their ability to pay in the future.
• Practitioners representing an obligor may consider talking to their client about setting up voluntary child support payments at the date of separation. Even if the amount is not perfectly calculated, these payments can reduce their future past support obligation and may create goodwill with the obligee.
  • It is difficult to provide evidence regarding voluntary payments made in cash or in kind (i.e. obligor provided a box of diapers). Payments made by check or by Cash App or Venmo are easier to prove.
• Providing evidence regarding the parties’ financial situations during the past support time period, step by step, in a clear and organized way, aids the court.
  • Avoid simply providing a lump sum amount for the entirety of the past support
    period.
  • Provide a break down of your calculation.

Past Support in Custody, Paternity, and Support Cases

• Minn. Stat. § 518A.82 was formerly Minn. Stat. § 256.87. The statute moved over to 518A on July 1, 2024 (with the revision effective August 1, 2025). Minn. Stat. § 518A.82 is almost identical to the last version of Minn. Stat. § 256.87.
• Minn. Stat. § 518A.82, Subd. 1 addresses past support for public assistance (PA):
  A parent of a child is liable for the amount of public assistance, as defined in section 518A.81, furnished to and for the benefit of the child, including any assistance furnished for the benefit of the caretaker of the child, which the parent has had the ability to pay. Ability to pay must be determined according to this chapter. The parent’s liability is limited to the two years immediately preceding the commencement of the action, except that where child support has been previously ordered, the state or county agency providing the assistance, as assignee of the obligee, shall be entitled to judgments for child support payments accruing within ten years preceding the date of the commencement of the action up to the full amount of assistance furnished. The action may be ordered by the state agency or county agency and shall be brought in the name of the county or in the name of the state agency against the parent for the recovery of the amount of assistance granted, together with the costs and disbursements of the action. Emphasis added.
• Minn. Stat. § 518A.82, Subd. 5 addresses past support for non-public assistance (NPA):
  A person or entity having physical custody of a dependent child not receiving public assistance as defined in section 518A.81 has a cause of action for child support against the child’s noncustodial parents. Upon a motion served on the noncustodial parent, the court shall order child support payments, including medical support and child care support, from the noncustodial parent under this chapter. A noncustodial parent’s liability may include up to the two years immediately preceding the commencement of the action. This subdivision applies only if the person or entity has physical custody with the consent of a custodial parent or approval of the court. Emphasis added.
• Minn. Stat. § 257.75, Subd. 3 notes that a ROP is a basis for bringing an action to award custody and to establish child support. The statute specifically notes that the child support obligation being established may include up to the two years immediately preceding the commencement of the action.
• Minn. Stat. § 257.66, Subd. 4 is a part of the Minnesota Parentage Act (MPA) and applies to paternity cases, the statute states:
  Support judgments or orders ordinarily shall be for periodic payments which may vary in amount. In the best interest of the child, a lump-sum payment may be ordered in lieu of periodic payments of support. The court shall limit the parent’s liability for past support of the child to the proportion of the expenses that the court deems just, which were incurred in the two years immediately preceding the commencement of the action. In determining the amount of the parent’s liability for past support, the court may deviate downward from the guidelines if:
  (1) the child for whom child support is sought is more than five years old and the obligor discovered or was informed of the existence of the parent and child relationship within one year of commencement of the action seeking child support;
  (2) the obligor is a custodian for or pays support for other children; and
  (3) the obligor’s family income is less than 175 percent of the federal poverty level.

Past Support in Marital Dissolution Cases

• Past support for married parties is determined as a part of the dissolution action, and is not determined in a support action (you do not utilize Minn. Stat. § 518A.82, formerly Minn. Stat. § 256.87 for married parties).
  • In re the Support of J.M.K. & S.R.K., 507 N.W.2d 459 (Minn. Ct. App. 1993)
• Generally past support can be requested back to the date of the commencement of the dissolution proceeding, but the court does have the power to order past support all the way back to the date of separation if it does so as a part of the final decree.
  • o Korf v. Korf, 553 N.W.2d 706 (Minn. Ct. App. 1996)
• Temporary motions may be a tool to be utilized regarding the retroactivity of support.
  • o Minn. Stat. § 518.131

Calculation Basics

• First, what is the past support time period?
  • When did the parties separate?
  • When was the action commenced?
  • What is the date two years prior to the date of commencement of the action?
• Second, are there any events that occurred during the past support time period which would impact the child support calculation? If so, you may need to change the calculation with the start of the new period after the change.
  • Birth of a nonjoint child
  • Loss of a job
  • Change of employment
  • Change in the guidelines calculator
    • The last major change in the calculator occurred between 2022 and 2023, but child care and medical assistance contribution tables change periodically.
  • Changes to the court ordered parenting time schedule (and thus the PEA)
• Third, what were the historical incomes of each party during the past support period?
• Fourth, what voluntary child support payments were made by the obligor to the obligee during the past support time period?
  • Did client pay the other party’s mortgage, rent, utilities? Did client buy diapers, groceries? Did client pay childcare? Did client give other party cash?
• Fifth, are past child care support, past medical support, or pregnancy and confinement expenses being requested in addition to past basic support?
  • If so, what evidence is there regarding these historic costs?
• Run a guidelines calculation for each section of the past support time period and provide these calculations to the court.