Letter Before Action: What It Is, When to Send It, and What It Must Include

A letter before action is the last thing you send before you go to court over an unpaid invoice, and for most UK small businesses, it's also the letter that finally gets a response.

Get it right and you either get paid within the deadline you set, or you walk into Money Claim Online with a paper trail a judge expects to see. Get it wrong and you can lose out on costs even after winning your case. Wrong wording, wrong deadline, or wrong process are all it takes.

This guide covers what a letter before action actually is, exactly when to send one, and what it must contain under the Pre-Action Protocol for Debt Claims, with a template you can adapt today.

1. What is a letter before action?

A letter before action, sometimes called a letter of claim, which is the term the courts actually use, is the final formal notice you send before starting a County Court claim for an unpaid invoice. It's different from every letter that came before it.

A reminder assumes good faith. A final demand adds urgency. A letter before action does something else entirely: it puts the debtor on formal notice that you intend to sue, tells them exactly what they owe and how you calculated it.

It also gives them one last, clearly defined window to pay or respond before you file a claim.

Courts treat it as a procedural step, not just a tone. The Civil Procedure Rules expect parties to try to resolve a dispute before using the court system, and a letter before action is the documented proof that you did. Send one properly and you're protected if the case ever reaches a judge. Skip it, or get the contents wrong, and a court can penalise you on costs in a claim you otherwise win outright.

You don't need a signed contract for any of this to apply. UK law implies a payment term into most business-to-business agreements even where nothing was put in writing: see our guide on getting paid with no written contract, and your right to chase, add interest, and eventually go to court exists regardless.

2. The Pre-Action Protocol for Debt Claims

Whether a letter before action is a strict legal requirement depends on who owes you the money.

If your debtor is an individual, including a sole trader, your letter is governed by a specific set of rules: the Pre-Action Protocol for Debt Claims, which has applied to business creditors chasing individuals and sole traders since 1 October 2017. It sets out, in detail, what your letter of claim must say, what you must send alongside it, and how long you must wait before you can issue a claim.

If your debtor is a limited company, this specific protocol doesn't technically apply. But you're not off the hook: the courts still expect you to have followed the general Practice Direction on Pre-Action Conduct, which asks for the same broad things in less prescriptive form: a clear letter, a fair deadline, and a genuine opportunity to pay or respond before you go to court.

Skip this step and the financial risk is real, not theoretical: a court can reduce or refuse your costs, or in worse cases order you to pay the debtor's costs, purely because you didn't give them a fair, well-documented chance to sort things out first, regardless of whether you were right about the debt all along.

3. When to send a letter before action

Send a letter before action once, and only once, three things are true: the debt is genuinely overdue, you've already sent at least one clear reminder and a final demand, and the debt isn't seriously disputed. If a client is querying the work itself, not just delaying payment, resolve that first; a letter before action on a disputed invoice can backfire.

In practice, that usually lands somewhere past day 30 of the original invoice being overdue, after a polite reminder, a firm chase, and a costed final demand have already been tried and ignored. There's no fixed law dictating this exact run-up (only the response window after you send the letter is fixed by the Protocol), but jumping straight to a letter before action on day one looks disproportionate, and courts notice.

For the earlier stages in full, including wording for each one, see our complete guide to chasing an unpaid invoice in the UK and our payment reminder templates guide.

4. What your letter before action must include

For an individual or sole trader debtor, the Protocol is specific about the content of your letter of claim and what you need to send with it.

If your debtor is a limited company, you don't need to attach the Reply Form or Financial Statement: those are specific to the Protocol for individuals and sole traders. But keep everything else: the exact amount, how interest was calculated, the basis of the debt, and a clear deadline. The substance matters more than the paperwork.

5. Adding statutory interest and compensation

Your letter before action should state the total you're claiming, not just the original invoice amount.

Under the Late Payment of Commercial Debts (Interest) Act 1998, UK businesses have a statutory right to add interest to an overdue business-to-business debt at the Bank of England base rate plus 8%, a combined rate of 11.75% a year, based on a base rate of 3.75% following the Monetary Policy Committee's most recent decision.

Checked 3 July 2026; the base rate can move at each MPC meeting, so confirm the current figure before you send a letter that quotes it.

On top of interest, you can add fixed compensation, between £40 and £100 depending on the size of the debt, without needing to prove you actually spent that much chasing it.

Recalculating the running total by hand every time you send a letter is exactly the kind of admin that accounting software like Sage^(affiliate) is built to automate, rather than a spreadsheet you have to remember to update.

State both figures in your letter, worked to the day if you can, so the total your debtor sees is the full amount you'll pursue through court if it isn't paid.

Read the full breakdown, including the compensation table by debt size, in our guide to statutory interest on late payments, or use our free late payment interest calculator to work out the exact figure for your invoice. If you haven't added interest to this debt before now, our step-by-step guide to charging interest on overdue invoices walks through the calculation from scratch.

6. Letter before action template

Adapt this for an individual or sole trader debtor. For a limited company, drop the line about the Reply Form and Financial Statement: everything else stays the same.

7. What happens after you send it

Once your letter before action is sent, there are three realistic outcomes.

They pay. This is what happens most often: a letter that names the Protocol, states an exact total, and sets a real deadline concentrates minds in a way three friendly emails never quite manage.

They respond, using the Reply Form or otherwise, to dispute the debt or ask for time. Read this properly rather than treating it as a stalling tactic. A genuine dispute needs sorting out before you go anywhere near court: judges don't look kindly on creditors who pushed ahead when the debtor had raised a real query.

A reasonable request for a payment plan is often worth accepting; a smaller amount paid reliably beats a larger amount fought over for months.

They ignore it. If the response window passes with no payment, no response, and no reasonable explanation, you're clear to issue a claim.

Whatever happens, keep your paperwork. Send the letter by a method that gives you proof, such as recorded post or email with a read confirmation if that's how you've corresponded throughout, and keep a copy of exactly what you sent and when. If this ends up in front of a judge, they will want to see that you followed the process properly, not just that you eventually filed a claim.

8. Common mistakes to avoid

• Sending it too early: before a reminder and final demand, or while the work itself is disputed.
• Missing the Reply Form and Financial Statement: required for individual and sole trader debtors, not optional extras.
• Getting the deadline wrong: it's a minimum of 30 days for Protocol-covered debtors, not the 7–14 days that's normal for a final demand.
• Vague figures: a total that doesn't show the original amount, interest, and compensation separately looks unprofessional and is harder to verify.
• Empty threats: quoting a court date you haven't booked, or consequences you can't actually deliver.
• No proof of sending: always keep evidence of when and how it was sent.

9. If it's ignored: Money Claim Online

If the response window closes with nothing, no payment, no dispute, or no proposal, your next step is Money Claim Online (MCOL), HM Courts & Tribunals Service's online system for straightforward claims up to £100,000. Most freelancer and small business invoices land on the small claims track, which is built around people without a solicitor.

You'll need the same figures you already put in your letter before action: the original amount, statutory interest calculated to the day, and fixed compensation. Court fees are set by the value of the claim, and if the debt is genuinely undefended, you can expect judgment well before you'd need to think about enforcement.

Not sure the numbers stack up? Our free small claims worth-it calculator weighs the fee and your time against what you'd recover before you file. We cover the whole process, including fees, timings, and what to expect if the debtor does respond, in our small claims court guide.

If chasing several invoices like this a month is becoming a pattern rather than an exception, it's worth weighing what a proper system costs against what late payment is already costing you in time: see our Pricing page for what's included at each plan.

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