How To Write a Demand Letter for an Unpaid Invoice (With Template)

A demand letter for an unpaid B2B invoice should contain six elements: debtor's full legal name, invoice number and amount, payment due date, applicable late payment interest, a specific deadline (14 days), and the consequences of non-payment. Below is a template you can use today. But first — a data point that might change your approach entirely.

You're writing this letter because polite emails didn't work. You're hoping the right words on the right letterhead will unlock the payment. And sometimes they do — demand letters sent by attorneys get a 90% response rate compared to 40% for self-written letters. That gap tells you something important about what actually moves a debtor: not your words, but who's sending them. Here's the template, when to use it, when to skip it entirely, and the moment it becomes a waste of your time.

[Your Company Name]

[Your Address]

[Date]

FORMAL DEMAND FOR PAYMENT

To: [Debtor Company Legal Name]

Attn: [Accounts Payable / Director Name]

[Debtor Address]

Re: Outstanding Invoice [#Number] — Amount Due: [Currency] [Amount]

Dear [Name],

This letter serves as formal notice that invoice [#Number], dated [Date], for [Currency] [Amount], remains unpaid. Payment was due on [Due Date] and is now [X] days overdue.

Under our agreed terms [and/or the EU Late Payment Directive 2011/7/EU], we are entitled to:

• The outstanding principal of [Currency] [Amount]
• Late payment interest at [ECB reference rate + 8%] from [Due Date], currently totalling [Currency] [Interest Amount]
• Fixed compensation of €40 for recovery costs

We request full payment of [Currency] [Total Including Interest] within 14 days of this letter.

If payment is not received by [Deadline Date], we will refer this matter to our professional collection partner / legal counsel without further notice.

We remain available to discuss a resolution. Please contact [Name/Phone/Email].

Yours sincerely,

[Name, Title]

A demand letter itself is not a court order — nobody goes to jail for ignoring one. But it serves three critical legal functions. It proves you made a formal demand (required before court action in many EU jurisdictions). It starts or confirms the interest clock on the overdue amount. And it creates a documented paper trail that strengthens your position if the case escalates to litigation.

In France, a mise en demeure is legally required before filing a court claim. In Germany, a Mahnung formally puts the debtor in Verzug (default). In the UK, a "letter before action" is expected under pre-action protocol. Skipping this step can weaken your case or delay proceedings.

Three outcomes, in order of likelihood.

The debtor pays. This happens more often than you'd expect — especially when the letter references specific legal provisions and a real deadline. The formality signals that the informal phase is over.

The debtor contacts you to negotiate. Partial payment, instalment plan, or a dispute they hadn't previously raised. This is actually a good outcome — engagement is better than silence, and most negotiations produce a recovery.

Nothing. Silence. The same void your emails disappeared into. This is the outcome that tells you the demand letter has done its job — not by producing payment, but by exhausting the amicable step and clearing the path for professional collection or legal action.

When the debtor has already demonstrated they don't respond to written communication. If you've sent three emails, a formal letter, and a follow-up — and received nothing — a fourth piece of paper won't change the dynamic. The debtor isn't ignoring your words; they're ignoring you.

At this point, the ROI of your time drafting another letter is negative. Professional collection changes the dynamic because a third party enters the picture — and the debtor's calculation shifts from "will they give up?" to "this has consequences."

The data is clear: attorney or professional collection letters get a 90% response rate. Self-written letters: 40%. The difference isn't the quality of writing — it's the credibility of the sender. A letter from your accounts department says "we'd like our money." A letter from a collection agency says "this has entered a process."

If the invoice is under €5,000 and the debtor is domestic, your own letter is a reasonable first step. For anything larger, international, or already past 60 days — the professional letter pays for itself.

The template above is yours to use. But the honest answer is: if you're Googling demand letter templates, you've probably already sent enough letters. The question isn't how to write a better one. It's whether writing is still the right strategy.

Contact us for a free assessment. We'll tell you whether a letter will work or whether it's time for a different approach.