Child Support Arrears: How Interest Works

When a support payment is missed, the unpaid amount becomes an arrearage. In many states each missed payment is automatically a final judgment the day it comes due, which means it generally cannot be erased later, only paid. Whether that balance then grows with interest depends entirely on state law.

A national count can hide the most important differences. Some rules run automatically, some begin only after judgment or a court finding, some are limited to agency cases, and some charges are penalties or surcharges rather than interest. Our current 50-state and DC research snapshot publishes those categories and leaves unresolved rates blank instead of converting them to zero.

Simple interest applies a rate to principal without adding accrued interest back into the base. Texas publishes a fixed 6 percent rule, California applies 10 percent to the unpaid principal of each installment judgment, and Massachusetts DOR applies 0.5 percent monthly to principal in qualifying full-service cases while expressly barring interest on interest or penalties.

Compounding is less common and still cannot be generalized. Colorado has different date-based regimes, and Kentucky’s rule applies after judgment entry. A current rate and method are not enough to reconstruct a balance when older installments fall under a different regime.

Zero, blank, and discretionary are three different results. Wyoming’s covered post-1990 installments bear no interest but can face a separate one-time 10 percent late penalty. Minnesota’s current no-interest rule has a historical boundary. Connecticut remains unresolved from the reviewed support-specific authority. Pennsylvania courts may award 6 percent on overdue support, so it is discretionary rather than a no-interest state.

Some rates float. Florida resets judgment rates quarterly, while New Hampshire, Nebraska, North Dakota, Utah, and other jurisdictions use rates tied to a year or published period. A current number should never be applied backward across a historical ledger without the period-by-period rate series.

Two jurisdictions with the same published percentage can produce different balances because of when the charge starts. Texas and California use installment-based triggers. New York’s award depends on judgment procedure and can depend on a willfulness finding. New Jersey ordinarily computes post-judgment interest at satisfaction or execution instead of adding a running monthly figure to the support ledger.

Ohio and Michigan gate the charge behind judicial findings. An Ohio court may assess interest only after the relevant willful-default finding at the applicable judgment rate. Michigan’s charge is a Treasury-indexed surcharge, not a universal fixed interest rate. Tennessee splits again: non-IV-D arrears generally use 6 percent subject to reduction, while IV-D arrears default to zero unless the court makes the required written finding, capped at 6 percent.

Georgia splits the difference: 7 percent per year starts 30 days after an installment comes due, but the court has discretion to waive or reduce it for hardship.

State child support agencies do not always compute the interest the statute allows. Illinois policy says the agency does not routinely calculate interest administratively. Washington DCS does not assess or collect it unless the interest has been reduced to judgment. So an agency principal balance can differ from a court interest calculation, and the legal and collection views must not be collapsed into one number.

Payment application order matters too. Whether a payment retires current support, principal arrears, or accrued interest first changes every later interest calculation. Our arrears calculators state the rate, the accrual rule, and the assumptions they apply for each state, and the court or agency figure always controls over any estimate.