How to write a demand letter for unpaid invoices

Published 26 September 2026 · Freelancing and getting paid

Most late invoices are paid after a clear, polite letter with a firm deadline. Here is how to write one that gets paid without damaging the relationship.

Not at the demand stage yet? Start with a payment reminder letter, and see the full plan for what to do when a client won't pay.

Before you write

• Check the contract or terms for the payment terms and any late payment interest clause.
• Gather the invoice numbers, dates, amounts and any partial payments.
• Check the notices clause for how formal notices must be sent.

What the letter should say

1. Who owes what. The customer's legal name, the amount outstanding, and the invoices it relates to.
2. What it was for and when it was due. One sentence each.
3. A deadline. Seven to fourteen days is common. Use the free deadline calculator to get the exact date.
4. How to pay. Bank details or a payment link, and a reference to quote.
5. Interest, if the contract allows it. In the UK, businesses can also claim statutory interest on late commercial payments.
6. An invitation to talk. If they dispute the invoice or need a payment plan, ask them to say so before the deadline.
7. What happens next. Collection, suspension of services or legal proceedings. Only mention steps you are prepared to take.

Tone

Stay factual. Threats you do not intend to carry out, or statements about the customer's honesty, can backfire and in some cases break debt collection rules. Consumer debts are regulated more strictly than business debts in most countries.

If they still do not pay

Many courts expect a formal pre-action letter before a claim is issued, and some prescribe what it must contain. Small claims courts are designed for business debts without lawyers. Check your local rules before starting proceedings.

Use the free template

The payment demand letter template includes optional invoice numbers, interest and next steps. Fill it in online and download a Word letter in a couple of minutes, without uploading customer details anywhere. For amounts in words, try the amount in words converter.

General information, not legal advice. Debt collection and pre-action rules vary by jurisdiction.

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