Back child support in Missouri, known legally as child support arrears, accrues simple interest at 1% per month (12% per year) under Mo. Rev. Stat. § 454.520, and the state has a 10-year window to collect each unpaid installment under Mo. Rev. Stat. § 516.350. The Missouri Family Support Division (FSD) enforces past due child support through wage withholding, tax intercepts, license suspension, and passport denial without filing a court case.
This guide explains how child support debt accumulates, how interest is calculated, the enforcement tools available, and the criminal consequences of failing to pay. Whether you are owed money or you owe a child support arrears balance, understanding Missouri's specific rules helps you protect your rights and avoid serious penalties.
Key Facts: Back Child Support in Missouri
| Factor | Missouri Rule | Statute |
|---|---|---|
| Interest on arrears | 1% per month (12% per year), simple interest | RSMo § 454.520 |
| Statute of limitations | 10 years from last recorded payment or judgment revival | RSMo § 516.350 |
| Enforcement agency | Family Support Division (FSD), Title IV-D | RSMo Chapter 454 |
| Retroactive modification | Only back to date of personal service of motion | RSMo § 452.370 |
| Criminal nonsupport | Class A misdemeanor; Class E felony if arrears exceed 12 monthly payments | RSMo § 568.040 |
| Passport denial threshold | Arrears over $2,500 | Federal 42 U.S.C. § 652(k) |
| Modification filing fee | Varies by circuit (roughly $0–$50 deposit) | RSMo § 452.345 |
What Is Back Child Support in Missouri?
Back child support in Missouri is the total unpaid amount of court-ordered support that has come due but was never paid, plus accrued interest. Each missed monthly installment becomes its own enforceable judgment under Mo. Rev. Stat. § 516.350, and these accumulate into a single arrears balance the obligor legally owes the obligee or the state.
Missouri treats child support arrears as a debt that cannot be discharged in bankruptcy and that carries the same protections as ongoing support. The terms past due child support, child support debt, and child support arrears all describe the same obligation. Importantly, this debt does not disappear when a child turns 18 or becomes emancipated. The ongoing duty to pay future support ends, but any arrears already accrued remain fully collectible. Missouri courts and the Family Support Division pursue these balances aggressively because the money represents support a child was legally entitled to receive. Both custodial parents and the state, when public assistance was paid, can hold an obligor accountable for the full historical amount owed plus statutory interest.
How Interest Accrues on Child Support Arrears
Interest on back child support in Missouri accrues at 1% per month, which equals 12% per year in simple interest, under Mo. Rev. Stat. § 454.520. This rate applies to all support judgments entered on or after September 1, 1982. Interest is calculated at the close of business on the last day of each month on the total arrearage existing that day, minus that month's current installment.
The statute specifies that the interest is simple, not compound, meaning it accrues only on the unpaid principal arrears rather than on previously accumulated interest. To illustrate the impact, a parent who owes $10,000 in past due child support accrues roughly $100 in interest each month, or about $1,200 over a single year. Over several years, interest can rival or exceed the original principal. A critical procedural rule under Mo. Rev. Stat. § 454.520 is that no payment is credited as interest until the entire support arrearage has been satisfied first. Payments always reduce principal before touching accrued interest. This interest is also classified as support for purposes of garnishment limits, exemptions, and nondischargeability in bankruptcy, giving it the same legal force as the underlying support obligation.
How to Collect Interest the State Won't Calculate
The Missouri Family Support Division does not calculate or collect interest on back child support for parents; the obligee must compute it independently and file a sworn affidavit with the circuit clerk under Mo. Rev. Stat. § 454.520. This affidavit is a condition precedent to executing on the interest, meaning no enforcement of interest is possible until the document is properly filed.
The affidavit must set forth the complete payment history of the obligor under the support order, along with a detailed statement showing exactly how the interest claimed was computed. Because the 1% monthly calculation must be performed installment by installment across potentially years of missed payments, the math is complex and error-prone. Many parents hire a family law attorney or a child support collection specialist to prepare the affidavit correctly, since a defective computation can be challenged by the obligor. While FSD will collect interest judgments already recorded on the circuit clerk's record, it will not create that record for you. This gap means thousands of dollars in legitimately owed interest go uncollected simply because the obligee never filed the required affidavit. If you are owed substantial child support arrears, calculating and documenting interest can significantly increase your total recovery.
Missouri's 10-Year Statute of Limitations
Missouri allows 10 years to collect each child support installment, measured from the date of the last payment recorded on the court record or from the most recent revival of the judgment, under Mo. Rev. Stat. § 516.350. After 10 years without a recorded payment or revival, an installment is presumed paid and becomes unenforceable.
This presumption-of-payment rule makes recordkeeping essential. Each periodic support payment functions as its own judgment, so the clock runs separately on each installment. Critically, payments must be entered on the official court record, which includes the automated child support system maintained by the Family Support Division or the family support payment center, to preserve enforceability. Informal cash payments made directly between parents that never reach the court record do not stop the 10-year clock. To keep older arrears collectible, an obligee can revive the judgment before the 10-year period lapses by filing the appropriate motion in the circuit court that entered the order. A separate, narrower five-year limit applies to retroactive paternity reimbursement actions under Mo. Rev. Stat. § 210.828. Because revival and accrual rules are highly fact-specific, parents nearing the 10-year mark on any installment should consult a Missouri family law attorney promptly.
Enforcement Tools the Family Support Division Uses
The Missouri Family Support Division can enforce back child support through income withholding, tax refund intercepts, property liens, license suspension, and passport denial, often acting administratively without a court hearing under RSMo Chapter 454. Employers must comply with income withholding orders, and federal law permits passport denial when arrears exceed $2,500.
Income withholding is the primary tool, with the obligor's employer deducting support directly from wages and remitting it to the family support payment center. Beyond wage garnishment, FSD intercepts state and federal income tax refunds, places liens on real and personal property including homes and vehicles, levies bank accounts, intercepts lottery winnings, and reports arrears to credit bureaus. The agency can suspend a delinquent parent's driver's license, professional licenses, and recreational licenses such as hunting and fishing permits. For interstate cases, FSD refers enforcement to other states' child support agencies. A parent facing these actions is not powerless: an attorney can file a motion to determine the exact amount of past due child support, present evidence of genuine financial hardship, seek modification of the ongoing obligation, or request a stay of license suspension or tax intercept when appropriate. Acting before enforcement escalates protects both income and licenses.
Comparison: Civil Enforcement vs. Criminal Nonsupport
Missouri pursues unpaid child support through two distinct tracks: civil enforcement to collect the money and criminal prosecution to punish willful nonpayment. The table below compares the two approaches and their consequences.
| Feature | Civil Enforcement | Criminal Nonsupport |
|---|---|---|
| Governing law | RSMo Chapter 454 | RSMo § 568.040 |
| Purpose | Collect arrears | Punish knowing failure to pay |
| Who initiates | FSD or obligee | Prosecuting attorney |
| Standard offense | N/A | Class A misdemeanor |
| Felony threshold | N/A | Arrears exceed 12 monthly payments = Class E felony |
| Possible penalties | Garnishment, liens, license loss | Jail, probation, fines |
| Arrears erased? | No | No (payment may be parole condition) |
Criminal Nonsupport Penalties in Missouri
Knowingly failing to provide court-ordered child support is criminal nonsupport in Missouri, charged as a Class A misdemeanor under Mo. Rev. Stat. § 568.040, and elevated to a Class E felony when the total arrearage exceeds the aggregate of 12 monthly payments. A felony conviction can carry a prison sentence of up to four years.
The statute requires that the failure to pay be knowing, meaning a parent who genuinely cannot pay despite good-faith effort has a potential defense, while a parent who has the ability to pay and chooses not to faces the most serious exposure. Prosecuting attorneys, not the Family Support Division, bring these charges, and FSD refers qualifying cases to county prosecutors. When a convicted obligor is placed on probation or parole, the court may order payment of current support plus satisfaction of arrears as a condition, beginning with a lump-sum payment the offender can afford and then periodic payments. Notably, even a criminal conviction does not erase the underlying child support debt. The arrears remain owed in full. Missouri law does permit expungement of a felony nonsupport record in limited circumstances after successful completion of probation and termination of the support obligation, offering a path to relief once the debt is resolved.
Can Back Child Support Be Reduced or Forgiven?
Missouri courts generally cannot retroactively reduce or forgive child support arrears that have already accrued; modification of a support order applies only to installments due after the date of personal service of the motion under Mo. Rev. Stat. § 452.370. This means filing a motion to modify changes future payments, not the existing child support debt.
To modify ongoing support, the moving party must show changed circumstances so substantial and continuing as to make the current terms unreasonable. A job loss, disability, or significant income change may justify lowering future obligations, but the motion only affects payments accruing after service. The narrow exceptions allowing any retroactive adjustment involve legal error, fraud, misrepresentation of income, or clerical mistakes in the original order. For example, a court may revisit a calculation if a parent concealed substantial earnings. The custodial parent who is owed arrears can voluntarily agree to compromise or forgive a portion of the debt, and FSD operates limited debt-compromise programs for state-owed arrears in some situations. However, an obligor cannot unilaterally escape accrued arrears. The most effective strategy is to file a modification motion immediately when circumstances change, since waiting only allows arrears to grow at the original rate plus 1% monthly interest.
How to Apply for Child Support Enforcement Services
Any custodial parent, noncustodial parent, or guardian can apply for free Missouri child support enforcement services through the Family Support Division, even when a court order already exists. You can apply online at myDSS.mo.gov, complete Form CS-300EZ, or call 1-800-859-7999 to begin a Title IV-D enforcement case.
Applying is essential because FSD cannot take any enforcement action on a case unless an application is on file, even if a valid court order already requires payment. The application asks for dates of birth, Social Security numbers, addresses, and court order information, so gathering these documents in advance speeds the process, which typically takes 30 minutes to over an hour. Completed paper applications are mailed to the Family Support Division at PO Box 6790, Jefferson City, Missouri 65102-6790. FSD serves custodial parents, noncustodial parents, legal guardians, adult children ages 18 to 21, and alleged fathers. The agency establishes paternity, establishes and reviews support orders, and enforces both child support and medical support. For case-specific questions where an order already exists, call 1-866-313-9960. Offices operate in each of Missouri's 114 counties plus the City of St. Louis, providing local access to enforcement help.