Three printed invoices fanned across a desk at 8pm, rain on the skylight.

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Can I send one letter before action for several unpaid invoices?

The short answer

Yes. The pre-action rules ask for concise details of the claim and how the amount is calculated1, and nothing limits a letter to one invoice. Set the invoices out in a statement with one deadline. The catch is the fixed sum: it follows the size of each debt, and each invoice is a debt of its own4, so £1,850, £2,400 and £950 earn £180, not the £70 that a £5,200 lump would3.

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.

The numbers

What changes with several invoices.

£180Fixed sums on the three example invoices: £70 + £70 + £40, not £70 on the total.3

14 daysFor a company to reply or pay, counted from the day you send the letter.1

30 daysTo reply, if the customer is a sole trader.2

6 yearsTo start a claim on each invoice. Each one has its own clock.9

What you can add

Three invoices, one letter, 9 October 2026

Say a design studio has three unpaid invoices to one client, all past their due dates. The letter goes out on 9 October 2026. All three went late in the second half of 2026, so the rate is 11.75%.

First invoice, due 15 July 2026£1,850.00
Second invoice, due 12 August 2026£2,400.00
Third invoice, due 9 September 2026£950.00
Interest: £1,850 × 11.75% ÷ 365 × 86 days7£51.22
Interest: £2,400 × 11.75% ÷ 365 × 58 days7£44.81
Interest: £950 × 11.75% ÷ 365 × 30 days7£9.17
Fixed sums: £70 + £70 + £40, one for each invoice3£180.00
Owed on 9 October 2026£5,485.20

Then it grows by £1.67 every day across the three until they pay. Pay-by date in the letter: 23 October 2026. Worked once on the £5,200 total, the fixed sum would be £70. That is £110 short.

The road ahead

Five steps. A court fee only if you get that far.

Step 1: List only the invoices already late
Oldest first. The fixed sum starts once interest starts to run3, so an invoice not yet due stays out and gets one line: "not yet due, not part of this claim".
Each invoice has its own six-year limit9, and the pre-action rules do not stop that clock1. Put the oldest at the top.
Cost: FreeTime: 15 minutes
Step 2: Work each invoice on its own
Interest starts the day after that invoice's due date, at 11.75% a year for invoices that went late in 20268: invoice × 11.75% ÷ 365 × days late. One that went late from 1 July to 31 December 2025 uses 12.25%, and from 1 January to 30 June 2025, 12.75%.
The fixed sum is £40, £70 or £100 by that invoice's own size3, added once for each.
Cost: FreeTime: 20 minutes
Step 3: Build the statement
One row per invoice: number, invoice date, due date, amount, days late on the day you send, interest, fixed sum. Then the totals and the daily figure. Attach a copy of every invoice and the terms it was sold on.
Cost: FreeTime: 30 minutes
Step 4: Send one letter with one deadline
Email the letter below, statement inside. For a company the pay-by date is 14 days from sending: the time the rules give a company to reply1 in a straightforward case.
A sole trader gets 30 days to reply2. The protocol wants the letter posted the day it is dated, with an information sheet, reply form and financial statement, and 14 days' notice before a claim if they reply and nothing is agreed: the full pack.
Not ready for the formal letter? A first nudge is one line: "Invoices 2041, 2057 and 2066 are overdue. Could you confirm the date they will be paid?"
Cost: FreeTime: Same day
Step 5: Deadline passed? Start one claim
Send no second final letter. Send one line naming the day the claim starts, or start it. One claim form can carry all the invoices10, and the court fee is worked on the total claimed: £455 for £5,000.01 to £10,00011.
Cost: £455 court feeTime: 20 minutes

A letter you can copy

Letter before action for several invoices

Send it once every invoice in it is past its due date and a short reminder has not worked.

New email

SubjectLetter before action: unpaid invoices , in total

Dear , has issued the invoices below. Each is past its due date and none has been paid. Copies of the invoices and the terms they were sold on are attached. Invoice | Dated | Due | Amount | Days late | Interest | Fixed sum Days late are counted to . Interest runs from the day after each invoice's due date, at 8% a year over the Bank of England base rate for the half-year that invoice went late (), under the Late Payment of Commercial Debts (Interest) Act 1998. The Act also gives a fixed sum for each invoice. Invoices: Interest to date: Fixed sums: Total due: Interest grows by a day until payment. Please pay the full amount, with the interest to the day you pay, by to: If you believe any of this is wrong, please tell me before that date and say why, naming the invoice. If it is not paid by then, I will start a claim in the County Court for all the invoices on one claim form, without further notice. Kind regards,

Tap a highlighted gap to see what goes in it.

Email it with each invoice and its terms attached as files, and keep the sent copy. It is written for a company: a sole trader needs the protocol's letter of claim, posted with its forms, as step 4 says. An invoice not yet due stays out of the rows. Add one line under them: "Invoice 2072 is not yet due and is not part of this claim." A disputed invoice goes in its own short section below the rows, so it cannot hold up the rest.

When not to bother

When it isn't worth it

One invoice carries its own late fee. If its contract sets a fair one, that fee applies instead6 of statutory interest: work it on the contract's terms, or send it separately.
One invoice is wholly disputed. Keep it out of the totals and deal with it on its own: what happens next when a client disputes an invoice.
The total is a few hundred pounds. A short, firm email does the job with less effort than a statement.
The company is in administration or liquidation. You claim through the insolvency, not a court claim: see claiming from a liquidator or administration.
They're a consumer, or you're in Scotland or Northern Ireland. The Act covers only sales between businesses5, and the steps here are for England and Wales.

The Wolf's note

One letter gives them one number and one date. Three letters give them three dates to choose from. List the oldest first, because the six years reach that one first.

Mr. Wolf · the AI inside WolfX

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