Back child support, arrears and interest
By the HowMuchChildSupport team · Published
Back child support, usually called arrears, is the total of payments that came due under an order and weren’t paid in full. It can build slowly, a partial payment here and a missed month there, or quickly after a job loss. Either way it behaves differently from most debts. It can’t be reduced retroactively, it often carries interest, and states have collection tools that other creditors don’t.
This guide explains how arrears accrue, how interest works state by state, how parents get back on track, and which federal enforcement tools apply. The arrears and interest calculator estimates a balance month by month using your state’s rules.
How arrears build up
Under 42 U.S.C. § 666(a)(9), every state must treat each child support payment as a judgment on the date it is due. That has important consequences. The unpaid amount can be enforced like any court judgment. It is recognized in every other state. And it can’t be modified retroactively: a court may change future payments, but not the ones already due, except back to the date the other parent was notified of a request to modify.
This is why the timing of a modification matters so much. A parent whose income falls but who waits months to ask for a change will owe the old amount for every month before the request. See how to modify a child support order and retroactive child support, which also covers support ordered for periods before a first order.
Arrears also outlive the order. When current support ends, because a child reaches the age in when child support ends or for another reason, any unpaid balance remains, and the payments that were going to current support often continue toward the arrears until they are paid.
Interest on unpaid support
Whether arrears grow depends on the state. Some charge a fixed yearly rate set in law, some use a rate an official resets periodically, some charge interest only when a court orders it, and some charge none. Grace periods and methods differ too: most rates are simple interest, but a few compound.
| State | Interest on arrears |
|---|---|
| Alabama | 7.5% a year |
| Alaska | 6% a year, simple |
| Arizona | 10% a year, simple |
| Arkansas | 10% a year |
| California | 10% a year, simple |
| Colorado | 10% a year, compounded |
| Connecticut | Only if a court orders it |
| Delaware | No interest |
| District of Columbia | No interest |
| Florida | A rate the state resets periodically |
| Georgia | 7% a year |
| Hawaii | Only if a court orders it (10% a year) |
| Idaho | A rate the state resets periodically |
| Illinois | 9% a year, simple |
| Indiana | Only if a court orders it (18% a year) |
| Iowa | 10% a year |
| Kansas | 10% a year |
| Kentucky | 12% a year, compounded |
| Louisiana | Only if a court orders it |
| Maine | Only if a court orders it (6% a year) |
| Maryland | Only if a court orders it (10% a year) |
| Massachusetts | 6% a year, simple |
| Michigan | Only if a court orders it |
| Minnesota | No interest |
| Mississippi | Only if a court orders it (8% a year) |
| Missouri | 12% a year, simple |
| Montana | Only if a court orders it |
| Nebraska | A rate the state resets periodically |
| Nevada | A rate the state resets periodically |
| New Hampshire | A rate the state resets periodically |
| New Jersey | A rate the state resets periodically |
| New Mexico | 4% a year |
| New York | Only if a court orders it (9% a year) |
| North Carolina | No interest |
| North Dakota | A rate the state resets periodically |
| Ohio | Only if a court orders it |
| Oklahoma | 2% a year, simple |
| Oregon | 9% a year, simple |
| Pennsylvania | No interest |
| Rhode Island | 12% a year |
| South Carolina | A rate the state resets periodically |
| South Dakota | 12% a year, simple |
| Tennessee | 6% a year |
| Texas | 6% a year, simple |
| Utah | A rate the state resets periodically |
| Vermont | 6% a year, simple |
| Virginia | 6% a year |
| Washington | 12% a year |
| West Virginia | 5% a year, simple |
| Wisconsin | 6% a year, simple |
| Wyoming | No interest |
The difference adds up. Suppose a parent missed $500 a month for a full year. By the start of the next year, the principal is $6,000. In Missouri, at 12% a year, interest adds $330. In Texas, which charges 6% and only on the unpaid amount above one month’s payment, interest adds $125. Each further year at those rates adds more, and in compounding states interest is charged on earlier interest too.
The official balance comes from the agency’s or court’s payment records, which reflect the exact dates payments arrived, how they were applied and whether a court waived any interest. Treat any calculator figure, including ours, as an estimate to check against those records.
Payment plans and getting current
Most arrears are repaid through an additional amount on top of current support. When a court or agency enforces an order through income withholding, federal rules require the withholding to include an amount toward overdue support, not just the current month. The arrears payment is set by the court or agency, often based on the size of the balance and the parent’s income, and it can be renegotiated.
Parents who owe arrears have several options worth knowing about. They can ask the agency for a payment agreement, which in many states can pause some enforcement actions while it is kept. Where arrears are owed to the state, usually because the children received public assistance, some states run programs that reduce the balance in exchange for regular payments. And if the current order is now too high, a modification can stop new arrears from building, even though it can’t erase old ones. For parents whose income is very low, low-income parents explains the self-support reserves and minimum orders that apply. Bankruptcy is not a way out: support arrears can’t be discharged, as child support and bankruptcy explains.
Parents who are owed arrears can ask the agency to open or update an enforcement case, request a payment history, and report a new job or address for the other parent. A private agreement to accept less may not be binding unless a court approves it.
Federal enforcement tools
States must have a standard set of collection tools for overdue support. They are covered in detail in how child support is enforced, but the main ones are:
- Income withholding. Support is deducted from pay before the parent receives it. Federal law limits the total to 50% of disposable earnings if the parent supports another spouse or child and 60% if not, plus 5% when support is more than 12 weeks overdue, under 15 U.S.C. § 1673.
- Federal tax refund offset. A tax refund can be taken toward past-due support once the balance reaches $500 in most agency cases, or $150 for support owed to the state, under 45 CFR 303.72.
- Passport denial. A parent certified as owing more than $2,500 can be refused a passport, under 42 U.S.C. § 652(k).
- Liens, credit reporting and license suspension. Overdue support creates liens on property, can be reported to credit bureaus, and can lead to suspension of driver’s, professional and recreational licenses.
These tools usually start automatically once a case meets the threshold, and many stop or ease once a payment plan is in place.
Using the arrears calculator
The arrears and interest calculator takes the monthly amount, the months missed and any payments made since, and applies your state’s interest rule. It’s useful for checking an agency statement, planning a payment schedule, or understanding what a lump sum would clear. If a new order is needed, the modification calculator shows the guideline amount under current circumstances. All figures are estimates; the agency’s or court’s records decide the balance, and courts can deviate from the guidelines when they set or change an order.