How to Write a Polite but Firm Overdue Invoice Email (With Templates)

Principles for overdue invoice emails

• Reference the specific invoice number, amount, and due date every time
• Assume good intent — the invoice may be stuck in accounts payable
• Escalate tone gradually over 2–3 weeks, not in the first email
• Attach the original invoice PDF to every message
• Keep emails short — busy clients skim, not read essays
• CC the project sponsor if the billing contact is unresponsive

Template 1: Friendly pre-due reminder (3 days before)

Subject: Reminder — Invoice #[NUMBER] due [DATE]

Hi [Name],

Hope you're well. A quick heads-up that Invoice #[NUMBER] for [PROJECT/SERVICE] — amount [CURRENCY][AMOUNT] — is due on [DATE].

I've attached the invoice for convenience. Please let me know if you need anything from my side to process payment.

Thank you,

[Your name]

Template 2: Due-date reminder (day of)

Subject: Invoice #[NUMBER] due today — [CURRENCY][AMOUNT]

Hi [Name],

Invoice #[NUMBER] for [PROJECT/SERVICE] is due today ([DATE]). Total: [CURRENCY][AMOUNT].

Payment details are on the attached invoice. Happy to resend bank details if helpful.

Best,

[Your name]

Template 3: Polite overdue notice (+3 days)

Subject: Overdue — Invoice #[NUMBER] ([CURRENCY][AMOUNT])

Hi [Name],

I wanted to follow up on Invoice #[NUMBER], which was due on [DATE] and remains outstanding. The balance is [CURRENCY][AMOUNT].

Could you confirm when payment will be processed? If there is a blocker on your end, I'm happy to help resolve it.

Invoice attached for reference.

Thank you,

[Your name]

Template 4: Firm follow-up (+7 days overdue)

Subject: Second notice — Invoice #[NUMBER] now 7 days overdue

Hi [Name],

I'm following up again on Invoice #[NUMBER] for [CURRENCY][AMOUNT], originally due [DATE]. Per our agreement, payment was due within [NET TERMS] of the invoice date.

Please arrange payment by [NEW DEADLINE — e.g. 5 business days] or let me know if there is a dispute I should address.

Regards,

[Your name]

Template 5: Final notice before late fees (+14 days)

Subject: Final notice — Invoice #[NUMBER] — late fee may apply

Hi [Name],

This is a final reminder that Invoice #[NUMBER] ([CURRENCY][AMOUNT]) is now [X] days overdue. Per our contract (Section [X]), a late fee of [X%] per month may apply to balances unpaid after [X] days.

Please remit payment by [DEADLINE] to avoid additional charges. If payment has already been sent, please share the transaction reference so I can reconcile.

Sincerely,

[Your name]

Only reference late fees if your contract includes them. Late fee enforceability varies by jurisdiction.

Tips that improve response rates

• Send emails Tuesday–Thursday mornings in the client's timezone
• Use the client's accounts payable email when you have it
• Include your payment details in the email body, not only the PDF
• Log every follow-up date in your invoice tracker
• If no response after 3 emails, call the project sponsor directly