How Long Can You Collect Interest on an Unpaid Invoice?

Q: How long do you have to collect interest on an unpaid invoice?

As long as the underlying debt is still legally collectible. Late-payment interest has no separate statute of limitations; it is part of the debt claim. Once the limitations period on the debt expires, the interest claim expires with it. The period varies: 6 years in the UK, 3 years in New York, 8 years in Ohio for contract claims, and 2 or 5 years in France depending on the transaction.

Q: Can you still collect interest if the client paid the invoice late?

Yes, if the contract or your terms provided for it. Paying the principal does not automatically erase accrued interest. Invoice the interest separately and promptly; waiting months to mention it makes collection harder in practice, even when you are legally entitled to it.

Q: Does getting a judgment extend how long you can collect?

Yes. A court judgment replaces the original limitations period with the judgment's own enforcement period, which in most US states runs about 10 years and can often be renewed. In the UK, a County Court Judgment effectively removes the 6-year limitation. That is one reason creditors sue before the original deadline: the judgment resets the clock.

Guides · Updated October 2026

The invoice is 14 months old. $8,400 for a website rebuild, due last August, and the client has gone quiet since November. Your contract says 1.5% per month on late payments, and at this point the interest alone is around $1,750. The question that finally lands in your inbox, usually at 11 PM, is how long you have to collect interest on an unpaid invoice before it evaporates. The answer is simpler than most people expect, and less comforting: the interest has no clock of its own. It lives exactly as long as the debt does, and it dies the day the debt becomes unenforceable.

Late-payment interest is not a separate claim with a separate statute of limitations. It rides on the underlying invoice the way a trailer rides on a truck. If you can still legally enforce the debt, you can still collect the interest your contract or the law provides for. Once the limitations period on the debt expires, the interest goes with it, no matter how carefully you calculated it. So the real question is always how long the debt itself stays alive, and that answer depends entirely on where you are.

The clock, state by state and country by country

In the UK, the Limitation Act 1980 gives creditors 6 years to pursue an unpaid invoice. If nobody pays and nobody acknowledges the debt in that window, it becomes statute-barred: the debt still exists in some abstract sense, but no court will enforce it, and the interest dies with it. One exception matters enormously. If a County Court Judgment is registered against the debtor, the limitation effectively falls away, and the judgment can be enforced indefinitely.

In the US it is a patchwork. New York gives creditors 3 years to sue on a debt, and under the Consumer Credit Fairness Act a partial payment no longer restarts that clock, which closed a favorite debt-collector trick. Kansas runs 3 years for oral contracts. Ohio runs 8 years for contract claims, one of the longer windows in the country. France splits it: 2 years for invoices to consumers, 5 years for business-to-business. The pattern underneath the patchwork is consistent. Written contracts usually get longer than oral ones, and business debts get longer than consumer ones, because the law assumes businesses keep records and consumers need protection.

One more clock worth knowing: prejudgment interest. In Florida, for example, courts routinely allow interest on liquidated commercial debts from the date of loss until judgment, even when the contract is silent on a rate, as long as the amount and the date it became due are provable. After judgment, post-judgment interest accrues under the state statute. This is why the documented timeline matters: the interest math is only as strong as the paper trail showing when the money was owed.

What two years of waiting actually costs

Line item	Amount
Invoice principal	$8,400
Interest: 1.5%/month x 14 months (simple)	$1,764
Total claim at month 14	$10,164

Simple interest at the contract rate. At month 14 the interest is over 20% of the principal. No wonder debtors stall, and no wonder creditors should not.

Working out what an old invoice is worth today?

Plug in the principal, rate, and days overdue for the exact figure.

Calculate the late-payment interest free

The timeline you should actually follow

The statute of limitations is the wrong number to plan around. It is the outer boundary, not a strategy. A debt that is legally alive but practically dead, debtor moved, records thin, witnesses gone, is worth the same as a time-barred one. The sequence that works in practice is much shorter than any statute.

Due date to 7 days overdue: send a short, neutral reminder and assume an oversight, especially with a first-time client. Days 7 to 30: follow up in writing, cite the invoice number, the amount, and the original due date, and ask for a payment date. Days 30 to 60: get firmer. State that the account is overdue, set a final payment date, and mention the late-payment interest your contract allows, with the running total. Days 60 to 90: formal demand letter, a call to a decision-maker, and pause any further work for that client. Beyond 90 days: weigh a collection agency, small-claims court, or an attorney against the size of the debt. A $900 invoice is rarely worth a lawyer. A $9,000 one often is.

The single discipline that makes all of this work is logging everything from day one. Timestamped invoices, timestamped follow-ups, timestamped promises. If you end up in front of a judge or a collections agency in year two, the question will not be whether your rate was reasonable. It will be whether you can prove the amount, the due date, and that you chased it. That paper trail is also what supports the prejudgment interest calculation, so it pays twice.

And one trap to avoid: in most places, a partial payment or a written acknowledgment of the debt can restart the limitations clock. New York is the notable exception for consumer debt. Know your jurisdiction's rule before you celebrate a $50 "good faith" payment, because in some states that payment just bought the debtor's delay and reset your deadline.

This is general information, not legal advice, and the exact periods and restart rules vary more than any article can catalog. If the amount is large enough to sue over, it is large enough for a 30-minute consult with a local attorney before the clock runs out.

Frequently asked questions

How long do you have to collect interest on an unpaid invoice?

As long as the underlying debt is legally collectible. Interest has no separate limitations period; it is part of the debt claim. Examples: 6 years in the UK, 3 years in New York, 8 years in Ohio for contract claims, 2 or 5 years in France. Once the debt is time-barred, the interest claim expires with it.

Does the statute of limitations apply to late payment interest separately?

No. Interest on an unpaid invoice is treated as part of the debt, not as its own claim with its own clock. Contract interest accrues for as long as the debt remains enforceable and stops being recoverable once the debt is time-barred.

Can you still collect interest if the client paid the invoice late?

Yes, if your contract or terms provided for it. Paying the principal does not automatically erase accrued interest. Invoice the interest separately and promptly; waiting months to mention it makes collection harder in practice.

Does getting a judgment extend how long you can collect?

Yes. A judgment replaces the original limitations period with its own enforcement period, about 10 years in most US states and often renewable. In the UK a County Court Judgment effectively removes the 6-year limit. That is one reason creditors sue before the original deadline: the judgment resets the clock.

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