What to do when a client won't pay your invoice (UK)

There is a version of this that ends with a court claim and a version that ends with a payment on Thursday. Which one you get is mostly decided in the first three weeks, before anybody has done anything dramatic.

What follows is the sequence that works, in order, with the decision points marked. It assumes the client is another UK business — the picture is different if you invoiced an individual or a sole trader, and that difference is flagged where it matters.

First, work out which problem you have

Almost every unpaid invoice is one of four things, and they need four different responses. Getting this wrong is the single most expensive mistake in credit control, because chasing harder is the correct answer to exactly one of them.

It got lost. Wrong email address, no purchase order, sitting in an accounts inbox nobody reads, or bounced off a supplier portal you did not know existed. Extremely common, and it looks identical to being ignored. The fix is a phone call to find out who actually processes invoices.

They are slow by design. The client pays everybody at 60 days regardless of what the invoice says. Nothing personal, nothing to escalate. The fix is structural: a conversation with their finance team, and different terms next time.

They are unhappy. Somebody thinks the work was wrong, or the scope was different, or the amount is not what they expected. They have not told you because raising it is awkward. This is a dispute, and it needs a completely different response — see below.

They cannot pay. The money is not there. Everything else you do is a race against other creditors, and speed matters more than politeness.

You cannot tell these apart from the outside. That is why the early chases are questions rather than demands: the fastest way to find out which one you are in is to ask in a way that is easy to answer honestly.

Week 0 — before it is late

The work that determines whether you get paid happens before the due date.

• Send the invoice to the person who pays it, not the person who briefed you. On anything over about £5,000, ask who that is at the point of quoting.
• Get the purchase order number on the invoice if the client uses them. An invoice without a PO at a mid-sized client is not late, it is invisible.
• Send a two-line note three days before the due date. Not a chase — a confirmation. "Invoice 1041 is due Friday, £8,400. Anything you need from us before then?" This catches the lost-invoice case while it is still free to fix.

Week 1 — the first chase

Send it one or two days after the due date, from a human, to a human. Short, friendly, and framed as a question rather than a complaint. The complete wording is in the templates guide; the shape is: name the invoice, name the amount, name the date it was due, ask whether it is scheduled.

Two things matter more than the words:

• One email covering everything they owe, not one per invoice. Three separate chases on the same morning reads as a machine and makes the total harder to see, which is the opposite of what you want.
• Attach the invoice again. Removes the most common excuse at no cost.

Week 2 — the phone call

If the first chase got no reply, stop emailing and pick up the phone. Not to apply pressure — to find out what is happening. Nine times out of ten you learn something you could not have learned by email: the invoice is in a portal, the approver is on leave, the PO was raised for the wrong amount.

Whatever you learn, write it down and confirm it back in an email the same day. "Thanks for the call — you'll get it into the 25th payment run." A promise that exists in writing is a promise you can hold someone to; a promise that exists only in a phone call is a promise nobody remembers making.

Week 3 — the formal chase

Now the tone changes, once. Not angry — formal. The distinction is that you stop asking and start stating.

This is the point to raise statutory interest. Every overdue business invoice in the UK accrues interest at 8% over the Bank of England base rate under the Late Payment of Commercial Debts (Interest) Act 1998, plus a fixed sum of £40, £70 or £100 per invoice depending on its size. You do not need a clause in your contract; the entitlement is automatic. The full mechanism and a worked calculation are here.

Mentioning that it exists at week three, without applying it, is usually more effective than applying it at week eight. It reframes the delay as something that has a cost, and it does so in the law's voice rather than yours.

Also at this point: check whether your contract lets you suspend work, and whether you want to. Read the clause before you mention it.

Week 4 to 6 — the letter before action

If the account is genuinely stuck and undisputed, the next step is a letter before action: a written demand setting out the debt, the interest, the deadline, and what happens if it is not met.

Note a real difference in the rules here. Where the debtor is an individual or a sole trader, the Pre-Action Protocol for Debt Claims applies and prescribes what your letter must contain and how long you must give them — normally 30 days. Where you are a limited company chasing another limited company, the protocol does not apply, and the general pre-action conduct rules give you more latitude. Getting this wrong at the individual end can cost you costs later. How to write one either way.

Week 6 onwards — the two real options

You now have two genuinely different routes, and they are not interchangeable.

A county court money claim. Suitable for debts of any size, including disputed ones, and the normal route if there is any argument about the work. Money Claim Online handles fixed-sum claims up to £100,000 against up to two defendants in England and Wales. The issue fee rises with the size of the claim, becoming a percentage of the value on larger ones, and is recoverable from the debtor if you win — read the current fee table before you budget, because it is reviewed periodically. Slow, safe, and it survives the client raising a defence.

A statutory demand, then a winding-up petition. Only for debts over £750 that are genuinely undisputed. You demand payment; if the company has not paid in 21 days, that failure raises a presumption of insolvency and you can petition to wind it up. It is dramatically faster and dramatically more dangerous: if the debt turns out to be disputed on substantial grounds, the petition gets dismissed and you can be liable for the costs. Choosing between them.

Before either, spend ten minutes on Companies House. Late accounts, a recently filed charge, a change of registered office, or a notice in The Gazette all change the answer — mostly by telling you to move faster and expect less.

If they say the work was wrong

Stop the chase. Immediately, and completely.

A dispute is not a slower version of non-payment; it is a different situation with different rules. Continuing to chase a disputed invoice achieves three bad things at once: it hardens the client's position, it forecloses the insolvency route (a debt disputed on substantial grounds cannot found a winding-up petition), and it reads badly if a judge ever sees the thread.

What to do instead:

1. Ask for the complaint in writing, specifically. Which invoice, which line, what is wrong with it.
2. Split the invoice. If £8,400 is disputed but £6,000 of it is not, ask for the undisputed part now and deal with the rest separately. Clients almost always agree to this, and it converts a stalled total into a partial payment plus a smaller argument.
3. Put a date on the resolution, not just on the payment.

If they cannot pay

Sometimes the honest answer is that the money is not there. A client who tells you that is doing you a favour, and the right response is a payment plan, not a court claim — a schedule you both sign up to, with dates and amounts, and a clear consequence for a missed instalment.

Two rules make plans work. The first instalment should be soon and small enough to be certain, because a plan that fails at instalment one was never a plan. And the schedule needs to be watched — the value of an instalment plan is entirely in somebody noticing on the morning the payment does not arrive, and saying so that day rather than three weeks later.

The thing that actually fixes it

Every step above is remedial. The reason agencies end up here is rarely a single bad client; it is that the whole book is a few days behind and nobody has time to look at it every morning.

The Xero Small Business Insights data for the UK put small businesses at 29.3 days to be paid in June 2026, of which 8.3 days were late. Eight days is not a crisis at any one client. Across a book of thirty open invoices it is most of a payroll cycle.

The agencies that do not have this problem are not the ones with the sharpest letters. They are the ones where somebody looks at every open invoice every day, sends the small nudge on the right morning, notices the promise that was broken, and escalates the two accounts that need it rather than the whole list. What that changed at one agency, and what it costs to make it somebody's job.

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General information for UK business-to-business debts, not legal advice on your contract. The escalation steps have real consequences — take advice before the insolvency route in particular.