Prejudgment interest rates by state range from about 4% to 15% per year, with most states landing between 6% and 10%. The rate that actually applies to your case depends on more than geography: it turns on the type of claim, whether a contract fixes its own rate, whether the defendant is a private party or a government entity, and when the interest clock started running. Two cases with identical damages in the same state can produce very different interest awards once those variables are sorted out.
The Range Across States
Every state has a statutory framework for prejudgment interest, but the structures differ. Most states use a fixed percentage that stays the same regardless of what the broader economy is doing. Fixed rates make settlement math predictable because both sides can calculate exposure from the start. A smaller group of states ties the rate to an external benchmark like the prime rate or a Treasury yield, so the effective rate shifts as the economy changes.
At the low end, some states set the default at 4% to 6% per year. At the high end, a few authorize 12% or 15% for certain claims, particularly those involving bad-faith conduct or intentional wrongdoing. The most common cluster sits at 8% to 10%. These are default rates, meaning they apply only when no contract or special statute points somewhere else. Many states also carry more than one rate on the books, using a lower number for claims against local governments and a higher one for commercial disputes.
Variable-rate states recalculate periodically. Some adjust monthly, others annually. A case that takes five years to reach trial in one of these states may involve several different rates applied across different segments of the timeline. That makes early estimates harder, but it keeps the rate closer to actual borrowing costs rather than a figure a legislature picked decades ago.
When the Interest Clock Starts
The start date drives the total almost as much as the rate does, and it gets less attention. A few months of difference on the front end can add tens of thousands of dollars to a judgment, especially at higher rates. State statutes generally point to one of three triggers: the date the loss occurred, the date the claimant made a formal demand for payment, or the date the lawsuit was filed.
Property damage and breach-of-contract claims often use the date of loss or breach. The reasoning is straightforward: the defendant has held onto money that belonged to someone else since that moment. Personal injury claims frequently delay accrual until the lawsuit is filed, because the value of a physical injury is harder to pin down immediately after the event than the value of an unpaid invoice.
Formal demand letters serve as a trigger in many breach-of-contract disputes. Once a claimant sends written notice of the specific amount owed, the defendant has the information needed to pay and stop the interest clock. Filing suit later does not necessarily move the start date forward if a valid demand is already on the record. These dates get contested aggressively when the interest number is large, so track them precisely.
Courts in some states can also pause the clock when the plaintiff caused significant delays: late notice of a claim, drawn-out discovery fights initiated by the plaintiff, or unreasonable scheduling refusals. The bar is high. Normal litigation pace does not count, and the delay generally has to be substantial and clearly attributable to the plaintiff.
Which Damages Qualify
Whether your damages are “liquidated” or “unliquidated” often determines whether you can collect prejudgment interest at all. Liquidated damages can be calculated with basic math: an unpaid invoice, a documented debt, a contractually specified sum. Because the defendant knows exactly what is owed from the start, courts have historically been comfortable awarding interest on these amounts from the date payment was due.
Unliquidated damages are the opposite. These are amounts nobody knows until a judge or jury decides at trial, such as pain and suffering, emotional distress, or the projected value of future lost income. The traditional rule denied prejudgment interest on unliquidated damages because the defendant had no way to know how much to pay to stop the clock. Most of the modern movement in prejudgment interest law is here: many states now allow interest on at least some unliquidated claims.
Courts increasingly ask whether damages are “calculable” rather than whether they were calculated. If the loss can be measured using fixed rules of evidence and known standards of value, many courts treat it as eligible for interest even if the exact figure was disputed. Two competing expert valuations do not automatically disqualify a claim, as long as both experts are applying math to measurable inputs rather than asking a jury to pick a number based on sympathy.
Damages that depend entirely on jury discretion, like the dollar value of defamation or the emotional toll of a particular wrong, remain ineligible for prejudgment interest in most states. If an accountant can build a spreadsheet that reaches the number, you have a strong argument for interest. If it takes a jury deliberation, you probably do not.
When a Contract Sets the Rate
In breach-of-contract cases, the contract itself often controls the interest rate rather than the state’s default statute. A large majority of states honor a contractual interest rate provision for prejudgment interest, applying whatever percentage the parties agreed to. A commercial lease specifying 12% annual interest on unpaid balances can produce a prejudgment interest rate of 12% even in a state whose statutory default is 6%.
There are limits. Many states cap the enforceable contract rate at a ceiling tied to the state’s usury statute. If the contract specifies a rate above the legal maximum, a court may reduce it to the cap or void the interest provision entirely. Consumer contracts face the strictest scrutiny. Several states limit prejudgment interest on consumer debt to the lower of the contract rate or the statutory rate, preventing creditors from stacking high interest provisions on top of already expensive credit.
When a contract is silent on interest, the state’s default statutory rate applies automatically. That is a drafting-stage issue, not just a litigation-stage one. Parties who want a specific rate to govern future disputes need to spell it out.
Government Defendants Pay Less, or Nothing
Suing a government changes the interest picture. Against the federal government, the default rule is that neither prejudgment nor post-judgment interest is recoverable unless a specific statute or contract expressly provides for it.1Office of the Law Revision Counsel. 28 USC 2516 – Interest on Claims Against the United States This is a direct extension of sovereign immunity.
The Federal Tort Claims Act makes the prohibition explicit: the government “shall not be liable for interest prior to judgment.”2Office of the Law Revision Counsel. 28 USC 2674 – Liability of United States A tort claim that would generate years of prejudgment interest against a private defendant generates zero against a federal agency. The same principle applies in the Court of Federal Claims, where interest requires a contract provision or express statutory authorization.1Office of the Law Revision Counsel. 28 USC 2516 – Interest on Claims Against the United States
State and local governments have their own versions of this protection. Many states cut the prejudgment interest rate for claims against municipalities and school districts, sometimes to half of the private-defendant rate. A few bar prejudgment interest against public entities entirely outside of contract claims. Check this early in any case against a public body, because it directly affects settlement value.
How Settlement Offers Cap Interest
A well-timed settlement offer can limit or eliminate a defendant’s prejudgment interest exposure. In federal court, Rule 68 allows a defending party to serve a formal offer of judgment at least 14 days before trial. If the plaintiff rejects the offer and ultimately wins less than the offer amount, the plaintiff must pay the costs incurred after the offer was made.3Legal Information Institute. Federal Rules of Civil Procedure Rule 68 – Offer of Judgment Rule 68 addresses “costs” rather than interest specifically, but the cost-shifting consequence pressures plaintiffs to take reasonable offers seriously.
Several states go further with statutes that tie settlement offers directly to interest accrual. A defendant who makes a written settlement offer within a specified window, often within the first 12 months after the lawsuit is filed, can cap interest exposure. If the final judgment comes in at or below the offer, the defendant owes no prejudgment interest at all. If the judgment exceeds the offer, interest is calculated only on the difference between the verdict and the offer, not on the full award. Defendants who make no qualifying offer face interest on the entire compensatory award.
Prejudgment interest is not a passive calculation. Defendants can actively manage exposure through early, reasonable offers, and plaintiffs who refuse reasonable offers may see their interest recovery sharply reduced.
Simple Versus Compound
Most states calculate prejudgment interest as simple interest, applying the percentage only to the original damage amount. A $100,000 award at 8% simple interest over three years produces $24,000 in interest, for a total of $124,000. Principal times rate times time.
Compounding adds each period’s interest to the running balance, so future interest accrues on a larger and larger number. Over short timelines the difference is modest, but across five or more years of litigation, compounding produces significantly higher totals than simple interest on the same principal. Federal post-judgment interest under 28 U.S.C. § 1961 compounds annually, one of the few contexts where compounding is the explicit statutory default.4Office of the Law Revision Counsel. 28 USC 1961 – Interest A contract can also specify compounding, and some states allow it when the parties agreed to it in writing. Without that specific authorization, expect simple interest.
How Federal Court Changes the Answer
Federal courts do not have a single, uniform prejudgment interest rate. The applicable rate depends on why the case is in federal court.
In diversity cases, federal courts apply state substantive law under the Erie doctrine.5Legal Information Institute. Erie Doctrine Courts have consistently treated the right to prejudgment interest as substantive, so the state’s rate and accrual rules follow the case into federal court. Filing federally instead of in state court does not change the calculation.
For claims arising under federal statutes, the analysis varies statute by statute. Some federal laws specify their own prejudgment interest rules. When a federal statute is silent, federal courts generally have discretion to award prejudgment interest and often look to the Treasury yield rate used for post-judgment interest under 28 U.S.C. § 1961 as a benchmark.4Office of the Law Revision Counsel. 28 USC 1961 – Interest That benchmark is based on the weekly average one-year constant maturity Treasury yield published by the Federal Reserve for the week before the judgment date.
Prejudgment interest ends the day judgment is entered. Post-judgment interest takes over from there, at its own rate, until the judgment is paid.
Taxes on the Interest Portion
Prejudgment interest is taxable income even when the underlying damages are tax-free. Damages for personal physical injuries are generally excluded from gross income under the federal tax code.6Internal Revenue Service. Tax Implications of Settlements and Judgments The interest awarded on top does not share that exclusion. The IRS treats prejudgment interest as ordinary interest income regardless of what it was calculated on, and federal courts have upheld this position repeatedly, reasoning that the interest compensates for the delay in payment rather than for the injury itself.
This catches plaintiffs off guard because the interest usually arrives inside a single lump-sum payment. If a settlement or verdict includes $500,000 in personal injury damages and $75,000 in prejudgment interest, the $500,000 may be tax-free but the $75,000 is reportable as interest income.7Internal Revenue Service. Settlements – Taxability A settlement agreement that does not separately allocate the interest portion does not erase the tax obligation. If interest was part of the underlying claim, a court may allocate a portion to interest regardless of how the agreement is drafted.
For defendants in business disputes, the picture is different. A defendant who pays prejudgment interest as part of a business-related judgment can generally deduct that payment as an ordinary business expense, provided the litigation arose from the taxpayer’s trade or business.8Internal Revenue Service. Chief Counsel Advice 200836025 The IRS has clarified that this deduction falls under the general business expense provision rather than the interest deduction provision, because the obligation to pay does not exist until the judgment is entered.