How to write a past due invoice letter (with a sample)

A past due invoice letter is a formal, written request for payment of an overdue balance. It carries more weight than an email reminder because it signals that the matter is being documented and may escalate.

When to send a formal letter

Most businesses send one after two or three email reminders have gone unanswered, typically when an invoice is 30 or more days late. It is also useful when the original contact has gone quiet and you need to reach a finance department or company address.

What to include

• Your business name, address and contact details.
• The customer's legal entity name and billing address.
• Invoice number, issue date, due date and amount outstanding.
• A summary of previous reminders and their dates.
• A specific deadline for payment.
• Accepted payment methods.
• What happens next if payment is not received, stated factually.

Sample past due invoice letter

Re: Overdue invoice #1042 — $2,400. Dear Accounts Payable, our records show that invoice #1042, issued on 10 September and due on 10 October, remains unpaid. We sent reminders on 13 October and 24 October and have not received payment or a response. Please arrange payment of $2,400 by 17 November using the details on the enclosed invoice. If you believe this invoice has been paid, or if there is an issue preventing payment, please contact us by that date so we can resolve it. If we do not hear from you, we will consider further steps to recover the balance. Sincerely, [Name].

Tone: firm, not threatening

State facts and next steps. Avoid threats you do not intend to carry out, and never misstate your legal position. Rules around collections language vary by jurisdiction and are stricter for consumer debts; see our collections compliance page for context.

After the letter

Diary the deadline. If it passes, decide: negotiate a payment plan, escalate formally, or write the balance off. A balance that sits in permanent follow-up costs attention and produces nothing.

Frequently asked questions

What is a past due letter?

A formal written request for payment of an invoice that has passed its due date, listing the amount, prior reminders and a deadline.

Should a past due letter be emailed or mailed?

Either works. Many businesses send a PDF by email and a printed copy to the billing address so there is a clear record of delivery.

How long after the due date should I send a past due letter?

Commonly around 30 days, after email reminders have not produced payment or a reply.