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What is a final demand letter, and when do I send one?

The short answer

Not a legal term. The court's pre-action rules don't use the name1: a final demand is a firm letter with the sum worked out, one pay-by date and what you will do if it passes. Send it when polite reminders have failed, usually two weeks after the due date. If it also holds what those rules ask for1, it is already a letter before action: one letter, both jobs.

Mara, WolfX research desk
Written with AI, checked by a person · 8 October 2026

England and Wales only. WolfX is software, not a law firm.

What you can add

A £2,800 invoice, 45 days late

Say you supplied goods to another business and invoiced £2,800, due on 24 August 2026. Your polite reminders have gone unanswered and nothing formal has gone. On 8 October it is 45 days late. It went late in the second half of 2026, so the rate is 8% over4 the Bank Rate on 30 June, which was 3.75%5: 11.75% a year. The final demand goes out on 8 October and asks for payment by 22 October.

£2,800.00The invoice

£40.56Interest: £2,800 × 11.75% ÷ 365 × 45 days2

£70.00Fixed sum (invoices from £1,000 to £9,999.99)3

£2,910.56Owed on 8 October 2026

From here interest adds £0.90 a day. The fixed sum stays at £70.00. If 22 October passes unpaid, the court fee to claim a sum like this is £1159.

The road ahead

Five steps. The only cost is a stamp.

Step 1: Send it once the polite ones have failed
The usual run: a reminder at day 7, this firm letter at day 14, then the letter before action at day 30. The law fixes none of those days. If you are further on and nothing formal has gone, send it now.
Cost: FreeTime: 2 minutes
Step 2: Work out the sum
Interest runs from the day after the due date6 at 8% over the base rate4, which is 11.75% a year5 on invoices that went late from 1 July to 31 December 2026.
Add the fixed sum3 once, and put both on a new invoice2. The working is in how to work out interest to the day.
Cost: FreeTime: 10 minutes
Step 3: Add what a letter before action adds
The court's Practice Direction1 usually looks for the basis of the claim, a summary of the facts, what you want and how the sum is worked out, plus the key documents, 14 days to reply and a look at talking or mediation. The letter below has all of it.
One letter can do both jobs: the court looks at whether you complied in substance1 and is not likely to mind technical slips. Leave the extras out and the letter before action comes second.
Cost: FreeTime: 15 minutes
Step 4: Send it by email and by post
Email it to whoever approves payments, with the invoice and the new invoice attached, and post a copy to the company's registered office or the address in your contract. Keep both and the proof of posting: two dated records of one letter.
Cost: A stampTime: 10 minutes
Step 5: Wait 14 days, then do what you wrote
The court's rules call 14 days1 reasonable in a straightforward case. The replies that count are payment, a date in writing or a dispute. Diary the date. For a dispute, see what happens next.
If the pay-by date passes with none of those, do not write a second 'final': it is a reminder with a bigger word on it. Do what the letter said and start the claim, or send the letter before action if you kept the two apart.
Cost: FreeTime: 14 days

A letter you can copy

Final demand that doubles as the letter before action

At day 14 in the usual run, send it cut down, as the last note says. From day 30, if nothing formal has gone yet, send it whole to a company: it is then your letter before action.

New email

SubjectInvoice : final demand, to be paid by

Dear , I supplied to your company, as agreed. Invoice , for , was due on . I have asked for payment before and have had neither payment nor a date. This is the last letter I will send before I start a claim. Under the Late Payment of Commercial Debts (Interest) Act 1998, interest has run on the invoice since the day after the due date, at a year, and a fixed sum for late payment is also due. A new invoice for both is attached. The amount owed is: Invoice: Interest to the date of this letter: , growing by a day Fixed sum: Total due today: Please pay the full amount by to: If it is not paid by then, I will start a claim in the County Court for the invoice, the interest and the fixed sum, without further notice. Copies of the invoice and of the order or contract are attached. If you believe any of this is wrong, please tell me before that date and say why. If it would help to talk it through, or to try mediation, I am willing to. Kind regards,

Tap a highlighted gap to see what goes in it.

Email it on the thread of your earlier reminders and post a copy, so both records carry a date. Keep the proof of posting. Keep it plain: no capitals for emphasis, no red type. The date does the work. Keep the claim sentence only if you will start the claim the morning after the pay-by date. A date you do not keep makes the next one worth less. If your contract sets its own interest rate, use that rate in place of the Act line. To keep the two letters apart, cut 'This is the last letter I will send before I start a claim', the claim sentence and the line about the papers. End with 'My next letter will be a letter before action', and send that at day 30.

When not to bother

When it isn't worth it

You have already sent a letter before action. Do not go backwards: a new demand only restarts the wait. The next move is the claim, and here is what to do if they ignored it.
They have promised a date in writing and it has not come yet. Wait for it, and put the day after in your diary. If it passes with nothing, the final demand goes the next morning.
They are a sole trader. The debt protocol8 wants its own letter of claim, posted with its Information Sheet, Reply Form and Financial Statement, and gives them 30 days. Keep this one apart (see the last note).
They dispute the invoice. A demand for the full sum does not settle a dispute. Ask in writing what they say is wrong, and chase the part they do not dispute first: see what happens next.
They are a consumer, or you are in Scotland or Northern Ireland. The interest and fixed sum cover only sales between businesses7. Scotland and Northern Ireland have their own court process10.

The Wolf's note

'Final' works once. A date that passes with nothing behind it makes the next date worth less. So write the date, write what happens on it, and be ready to do that the next morning.

Mr. Wolf · the AI inside WolfX

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