When friendly payment reminders stop working, a formal demand letter is your next step. A well-drafted demand letter signals that you are serious about recovering what you're owed and often prompts payment without requiring court action. Here's how to write one that works.
The Escalation Sequence
Before sending a formal demand letter, you should have already sent at least two informal reminders. A typical sequence looks like this:
- Day 1: Invoice sent
- Day of due date: Friendly reminder if not yet paid
- 7 days overdue: Second reminder, slightly more direct
- 14-21 days overdue: Phone call if possible
- 30+ days overdue: Formal demand letter
Moving to a formal demand too early can damage the client relationship unnecessarily. But waiting too long allows the debt to age and makes recovery harder. 30 days overdue is usually the right threshold.
What a Demand Letter Must Include
A formal late payment demand letter should contain all of the following:
- Your full name and contact details
- Client's full name and address
- Date of the letter
- Clear subject line: "Formal Demand for Payment — Invoice #[number]"
- Invoice details: Invoice number, date, amount, services provided
- Original due date
- Number of days overdue
- Late payment interest calculated to date (if applicable)
- Total amount now owed
- New payment deadline: Typically 7-14 days from the letter date
- Consequences of non-payment: Legal action, debt collection, credit reporting
- Payment instructions
Demand Letter Template
Use this as a starting point and adapt it to your situation:
[Your Name]
[Your Address]
[Date]
[Client Name]
[Client Address]
FORMAL DEMAND FOR PAYMENT — Invoice #[NUMBER]
Dear [Client Name],
I am writing to formally demand immediate payment of the outstanding invoice detailed below.
Invoice #[number] dated [date] for [description of services] in the amount of [amount] was due on [due date] and remains unpaid. Despite previous reminders on [dates], no payment has been received.
The total amount now outstanding is [original invoice amount] plus late payment interest of [amount] calculated at [rate] per annum from [due date] to [today's date], making the total sum of [total amount].
I require payment of [total amount] to be made by [date — 7-14 days from letter date] by [payment method/bank details].
If payment is not received by the above date, I will have no choice but to pursue recovery through [small claims court / a debt collection agency / legal proceedings], without further notice. You will also be liable for any additional costs incurred in recovering this debt.
Yours sincerely,
[Your Name]
Tone and Presentation
A demand letter should be:
- Formal and professional: No emotional language, no threats beyond what you actually intend to do
- Factual: Stick to dates, amounts, and facts
- Clear: State exactly what is owed and when payment is required
- Credible: Only threaten consequences you are actually prepared to follow through on
Send the letter by email with read receipt AND by recorded post if the debt is significant. Keep copies of everything.
Adding Late Payment Interest
If your contract includes a late payment interest clause (and it should), calculate and add the interest to the demand. In the UK, even without a contractual clause, the Late Payment of Commercial Debts Act gives you the right to charge 8% above Bank of England base rate on business-to-business invoices, plus compensation of £40-£100 per invoice.
Use our Late Payment Calculator to calculate the interest and compensation owed automatically.
What to Do If They Still Don't Pay
If the demand letter deadline passes without payment:
- Small claims court: UK up to £10,000 (England/Wales), US typically $5,000-$25,000 depending on state. Relatively quick and inexpensive. No lawyer required.
- Debt collection agency: Works on a commission basis. Effective for smaller debts where court proceedings aren't cost-effective.
- Solicitor/attorney letter: A letter from a lawyer carries significantly more weight than one from you directly and often prompts immediate payment.
For the full process, see our guide on handling non-paying clients.
Calculate Your Late Payment Interest
Use our free calculator to instantly compute the interest and compensation owed on your overdue invoice.
Calculate Interest →Frequently Asked Questions
When should I send a formal demand letter for late payment?
Send a formal demand letter after at least two informal reminders have been ignored. Typically this means the invoice is 30+ days overdue. A formal demand letter signals you are prepared to take legal action and often prompts payment where informal chasers have failed.
Does a demand letter need to be sent by post or can I email it?
Email is legally effective and creates a clear timestamped record. For maximum formality — particularly if you anticipate court proceedings — send by recorded delivery (UK) or certified mail (US) in addition to email. Keep proof of sending.
How much late payment interest can I charge?
In the UK, the Late Payment Act allows 8% above Bank of England base rate on B2B debts. In the US, the rate depends on your contract and state law. Always specify your interest rate in the original contract.
What happens if the client ignores my demand letter?
Your options are: small claims court, a debt collection agency, or engaging a solicitor/attorney. In the UK, you can also add late payment interest and compensation on top of the original invoice amount.
Can I add my legal costs to the debt if I take a client to court?
In small claims court you can usually recover the court filing fee. In the UK, the Late Payment Act allows recovery of a fixed compensation fee plus reasonable recovery costs. In the US, attorney fees are recoverable only if your contract includes a fee-shifting clause.