How old can an unpaid invoice be? The 6-year limitation period

Most unpaid invoices are chased within weeks. But some slip through: a disputed job parked for later, a customer who kept promising to pay, or a ledger inherited after a staff change. Before you spend time or money chasing an old invoice, check whether it is still legally recoverable and how strong your evidence still is. This guide explains the limitation period for business debts, when the clock starts, what restarts it, and what to do with invoices that are getting old.

This guide is general information for UK businesses, not legal advice. Statutory references were checked on legislation.gov.uk on 23 October 2026. Primary reading: the Limitation Act 1980, sections 5, 8, 29, 30 and 32. Take advice from a solicitor if a large debt is close to six years old.

The basic rule: six years for an ordinary contract debt

Section 5 of the Limitation Act 1980 says an action founded on simple contract cannot be brought after six years from the date the cause of action accrued. An unpaid invoice under trade terms, a purchase order, an emailed quote that was accepted or a verbal agreement is a simple contract debt, so the six-year rule applies.

“Brought” means the claim is issued at court. Sending reminders, a final demand or a letter before action does not stop the clock on its own. Limitation is a defence the debtor has to raise, but if it applies it defeats the claim completely, including any statutory interest and fixed compensation.

When does the clock start?

The cause of action accrues when the debtor is in breach, which for an invoice is normally the date payment fell due under the contract.

The dates above are illustrations of how the period is counted, not advice on a specific debt. If you are anywhere near the end of the period, take advice rather than relying on a calculation to the day. See also when a commercial invoice is legally late.

What restarts the six years

Section 29(5) gives the creditor a fresh start where the debtor either acknowledges the debt or makes a payment in respect of it. The right of action is then treated as accruing on the date of the acknowledgment or payment.

• Part payment. Any payment towards the debt restarts the clock for the balance. Keep the bank record and any remittance showing which invoice it was for.
• Written, signed acknowledgment. Section 30 requires it to be in writing and signed by the debtor or its agent. A letter or email from a director or authorised person accepting the amount, or proposing a payment plan for it, is the kind of evidence to keep.
• Repeated extensions. Section 29(7) allows the period to be extended again and again by further payments or acknowledgments while it is still running.

What does not restart it: phone calls, a verbal promise, your own reminders, or silence. And once the six years have passed, section 29(7) is clear that a later acknowledgment or payment cannot revive the claim.

Other periods worth knowing

Being in time is not the same as being collectable

A debt can be well inside six years and still be hard to recover. Companies dissolve, directors move on, documents are lost and memories fade. Before chasing an older invoice, check:

1. The company still exists. Search the Companies House register for its status and any insolvency; see insolvency warning signs.
2. You can prove the debt. Contract or order, delivery or completion evidence, the invoice and any later acknowledgment; see the proof of debt checklist.
3. It is not genuinely disputed. An old dispute that was never resolved needs dealing with first; see disputed commercial invoices.
4. You know the right legal entity. A trading name or a group company may not be the party that owes you; see recovering unpaid invoices from a limited company.

What to do with an ageing invoice

1. Write down the key dates now: the due date, any later payments and any written acknowledgments, so you know when the period ends.
2. Ask for a written acknowledgment or a payment. A signed letter accepting the balance, or even a small payment, restarts the clock while you negotiate.
3. Escalate in writing with a final demand and a letter before action that give a clear deadline. For claims against a sole trader, the Pre-Action Protocol for Debt Claims applies.
4. Do not leave court action to the last month. If the debtor still will not pay and time is short, take advice on issuing a county court claim before the deadline.
5. Consider a collection partner for an undisputed debt owed by a Ltd, LLP or PLC; see aged debt over 90 days.

Frequently asked questions

How old can an unpaid invoice be before you can no longer recover it? In England and Wales a claim for an unpaid invoice under an ordinary contract must be issued at court within six years of the date the cause of action accrued, under section 5 of the Limitation Act 1980. That is normally the date payment fell due, not the invoice date. After six years the debtor can rely on limitation as a complete defence.

Does the six years start from the invoice date or the due date? Usually from the date payment became due under the contract. If your terms say 30 days from invoice, the clock normally starts when those 30 days end. Where there are no agreed terms it can be argued that payment was due on delivery or completion, so keep evidence of when the work or goods were supplied.

Does a part payment restart the limitation period? Yes. Under section 29(5) of the Limitation Act 1980, if the debtor makes a payment in respect of the debt, the right of action is treated as accruing again on the date of that payment. A new six-year period runs from then for the balance.

Does an email from the debtor admitting the debt count? It can. Section 30 requires an acknowledgment to be in writing and signed by the person making it, or their agent. Whether a particular email counts as signed depends on the facts, so a clear letter or email from a director or authorised person accepting the amount owed is the safest evidence. A phone call does not count.

Can an acknowledgment revive a debt that is already over six years old? No. Section 29(7) says a current limitation period can be extended repeatedly by further acknowledgments or payments, but once a right of action is barred it cannot be revived by a later acknowledgment or payment.

Is the limitation period different if the contract was signed as a deed? Yes. An action on a deed (a specialty) has a 12-year limit under section 8 of the Limitation Act 1980. Most trade terms and purchase orders are simple contracts, so the six-year rule is the one that normally applies.

Does the same rule apply in Scotland and Northern Ireland? No. This guide covers England and Wales. Scotland uses a separate prescription system, under which most contract debts are extinguished after five years, and Northern Ireland has its own limitation legislation. Take local advice if the debtor or the contract is outside England and Wales.

Will your partner take on an old debt? Older debts are harder to collect because evidence fades and companies change or close, and debts near or past six years may be declined. We are an introducer, not solicitors or an FCA-authorised firm. Where a debt owed by a Ltd, LLP or PLC is accepted, the fee is 15% of what is recovered, payable only when you have been paid. Recovery is not guaranteed.

If you have an undisputed invoice owed by a Ltd, LLP or PLC that is getting old, do not wait for it to get older. Upload the invoice via business debt collection or read how no collection, no fee works. The fee is 15% of what is recovered, payable only when you have been paid. Recovery is not guaranteed.