What post-judgment interest actually is
Post-judgment interest accrues on the unpaid amount of a money judgment — the principal, and in many jurisdictions the costs and prejudgment interest folded into it — from the moment the judgment is entered. It exists for a straightforward reason: a dollar collected years after you win is worth less than a dollar on the day you won, and a debtor who drags out payment should not profit from the delay.
Two features make it powerful. First, it is usually automatic: in most jurisdictions it accrues by operation of statute, without a separate court order, so you do not have to ask for it — but you do have to calculate it and claim it when you collect. Second, it runs until the judgment is satisfied, so a large award left unpaid for years can accumulate interest that rivals the original judgment.
The federal rule: 28 U.S.C. §1961
In federal district court, a single statute governs nearly all civil money judgments: 28 U.S.C. §1961. It sets the rate equal to the weekly average one-year constant-maturity Treasury yield for the calendar week preceding the date the judgment is entered, as published by the Federal Reserve. The interest is compounded annually and — importantly — is fixed as of that week for the entire life of the judgment. Even if Treasury yields swing wildly afterward, the judgment keeps accruing at the rate set the week before it was entered.
Because that benchmark moves every week, there is no single "federal rate" to memorize. We track the underlying one-year Treasury series and publish the derived federal post-judgment rate so you can read the exact figure for the week you need. For how we compute it from the Federal Reserve's H.15 release, see our methodology.
Fifty states, fifty rules
Leave federal court and the tidy single rule dissolves. State post-judgment interest tends to fall into a few broad patterns:
- Fixed statutory rates — a flat number written into the code that changes only when the legislature amends it. Easy to apply, but it can sit far above or below the market for years.
- Market-linked formulas — a moving benchmark (a Treasury yield, the prime rate, or a state discount rate) plus a fixed margin, often reset annually or quarterly.
- Dual or claim-specific rates — a different rate depending on the kind of case: contract versus tort, judgments against a government entity, or a special rate for categories such as medical malpractice.
Some states fix the rate at entry; others let it float over the life of the judgment. The only safe move is to check the specific jurisdiction. Our state judgment-interest hub lists each state's rule and the statute behind it, and the state judgment interest calculator applies the right structure for you.
Simple vs. compound: the detail that quietly moves the number
How interest is applied matters as much as the rate itself. Simple interest accrues only on the original judgment amount. Compound interest periodically adds the accrued interest to the balance, so future interest is figured on a growing total.
Consider an illustrative example. On a $100,000 judgment at, for example, 5% simple annual interest, the debt accrues $5,000 a year — roughly $13.70 a day — so after three years you are owed $15,000 in interest. Under annual compounding at the same 5%, year two's interest is figured on $105,000 and year three's on $110,250, and the same three years produce about $15,760. The gap is modest here, but it widens sharply with higher rates, larger judgments, and longer delays. Federal judgments compound annually; many states use simple interest and a few compound — one more reason to confirm the rule that applies to yours.
When the clock starts — and when it stops
The start date is usually the date the judgment is entered on the court's docket — not the date of the verdict, the loss, or the filing. Interest for the period before judgment is a separate animal; see prejudgment interest for that side of the ledger. The clock stops when the judgment is satisfied — paid in full, including the accrued interest itself.
A few wrinkles catch people out. An appeal generally does not pause accrual: interest keeps running while the case is on appeal, and if the judgment is affirmed it typically runs from the original entry date. A partial payment usually reduces the balance on which future interest accrues, but jurisdictions differ on whether a payment applies first to interest or to principal. And an amended or renewed judgment can reset or restart the calculation. When timing is contested, the daily figure — the "per diem" — becomes the number everyone argues over.
How a creditor puts it to work
For the party owed money, post-judgment interest is both leverage and arithmetic. In practice you will:
- Identify the governing rule — federal §1961, or the specific state statute — and the exact rate for your judgment's date.
- Compute a per diem so you can state the payoff as of any future date, which matters for settlement letters, writs of execution, and satisfaction filings.
- Update the payoff as time passes and as partial payments arrive.
Because the payoff is a moving target, most creditors recalculate it each time they collect or negotiate. Run your judgment through the post-judgment interest calculator, or browse the full set of statutory-interest calculators when a matter involves more than one kind of interest.
Two cautions. Rates and even the formulas change, so never rely on a figure you remember — pull the current published number. And this guide is general information, not legal advice: the controlling authority is your jurisdiction's statute and your court's own rules, so verify the rate, the accrual method, and the dates against the official source before you rely on them.