A past due invoice reminder is a polite message sent to a customer after an invoice has passed its payment due date. The best reminder clearly states the invoice number, amount owed, original due date, and how the customer can make payment without sounding unnecessarily aggressive.
Late invoices are a normal part of running a business, but ignoring them can create serious cash-flow problems.
A 2026 QuickBooks report found that 59% of surveyed small businesses had invoices unpaid for more than 30 days, with businesses reporting an average of $17,700 waiting to be collected.
That makes a simple payment reminder more than just an administrative task. A well-written message can help you recover money while maintaining a professional relationship with the customer.
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Table of Contents
What Is a Past Due Invoice Reminder?
A past due invoice reminder is a follow-up communication sent when a customer has not paid an invoice by the agreed deadline.
The reminder may be sent by email, text message, accounting software, or even by phone. Its purpose is to bring the unpaid balance to the customer’s attention and make it easy for them to resolve the payment.
For example, if Invoice #1042 was due on September 25 and payment has not been received, you could send:
Hi Sarah, this is a friendly reminder that Invoice #1042 for $1,250 was due on September 25. We haven’t received payment yet. Please let us know if you need another copy of the invoice or have any questions about the payment.
The first reminder does not need to sound like a collection notice. In many cases, the customer may have simply missed the invoice, overlooked the due date, or experienced an internal payment-processing delay.
Why Should You Send a Past Due Invoice Reminder?
An unpaid invoice represents work, products, or services that have already been delivered but have not yet generated the expected cash flow.
For small businesses, several unpaid invoices can quickly become a financial problem. QuickBooks’ 2026 Small Business Late Payments Report found that businesses with overdue invoices reported significant cash-flow challenges.
A reminder also creates a written record of your attempts to collect payment. This can become useful if an invoice remains unpaid and you eventually need to escalate the matter according to your contract or applicable laws.
Most importantly, sending a reminder promptly gives the customer an opportunity to resolve a simple oversight before the situation becomes more complicated.
What Should a Past Due Invoice Reminder Include?
A useful reminder should make it possible for the customer to understand the situation without searching through old emails.
Include these details:
- Customer’s name
- Invoice number
- Invoice date
- Original due date
- Outstanding amount
- Number of days overdue, when useful
- Payment instructions or payment link
- Your contact information
- A clear request for payment
- An offer to help resolve any issue
For example:
Invoice: #1042
Original due date: September 25, 2026
Outstanding balance: $1,250
Status: 8 days past due
Clear information reduces unnecessary back-and-forth. Stripe recommends including important invoice details and making payment instructions clear when following up on unpaid invoices.
When Should You Send a Past Due Invoice Reminder?
There is no single schedule that works for every business, but a gradual approach is usually easier for maintaining customer relationships.
1. Before the due date
A reminder before the due date is not technically a past due reminder, but it can prevent an invoice from becoming overdue.
For example, you could send a friendly message one to three days before payment is due:
Just a quick reminder that Invoice #1042 for $1,250 is due on September 25. Please let us know if you have any questions or need another copy of the invoice.
Xero recommends using reminders before invoices are due as part of a structured collection process.
2. One to three days after the due date
This is a good time for a friendly follow-up.
Do not immediately assume that the customer is deliberately refusing to pay. Ask whether they received the invoice and whether anything is preventing payment.
3. About one to two weeks overdue
At this point, your message can become more direct.
Mention that the invoice remains unpaid and ask the customer to provide a payment date. If there is a dispute, encourage them to explain the problem so you can address it.
4. Around 30 days overdue
A 30-day overdue invoice deserves a more formal follow-up.
Restate the balance, reference the original payment terms, and clearly explain what you need from the customer. If your contract provides for late fees or other consequences, mention them only according to the agreed terms.
Stripe recommends having a systematic follow-up process rather than waiting indefinitely for an unpaid invoice to resolve itself.
Past Due Invoice Reminder Template
Here is a simple template you can customize for most situations:
Subject: Past Due Invoice #[Invoice Number] – Payment Reminder
Hi [Customer Name],
I’m following up regarding Invoice #[Invoice Number] for [Amount], which was due on [Due Date].
According to our records, we have not yet received payment. Please arrange payment at your earliest convenience.
If payment has already been sent, please disregard this message and let us know so we can update our records.
If you have any questions about the invoice or need another copy, please let me know.
Thank you,
[Your Name]
[Business Name]
[Phone Number]
[Email Address]
Past Due Invoice Reminder Email Example
Suppose a web designer has completed a $1,800 website project and the invoice was due 10 days ago.
A natural reminder could look like this:
Subject: Friendly Reminder – Invoice #WD-1082
Hi Michael,
I hope you’re doing well. I’m following up on Invoice #WD-1082 for $1,800, which was due on September 23.
We haven’t received the payment yet. Could you please let me know when we can expect payment?
If you need me to resend the invoice or provide any additional information for your accounting department, I’m happy to help.
Thank you,
James
James Web Design
This approach is direct without being unnecessarily confrontational.
Gentle Reminder for Payment Message
For a long-term customer or an invoice that is only a few days overdue, a shorter message may work better.
Hi [Name], just a quick reminder that Invoice #[Number] for [Amount] was due on [Date]. We haven’t received payment yet, so I wanted to check whether everything is okay on your end. Please let me know if you need anything from me. Thank you!
This wording assumes that the delay may be accidental while still clearly communicating that payment is outstanding.
Past Due Invoice Reminder for a Long-Standing Client
Existing customers may deserve a slightly warmer tone, especially when they normally pay on time.
Subject: Checking In About Invoice #[Number]
Hi [Name],
I wanted to check in about Invoice #[Number] for [Amount], which was due on [Date].
I know things can sometimes get delayed, so I wanted to make sure the invoice reached you and that there aren’t any issues holding up payment.
Please let me know when you have a chance. I’m happy to resend the invoice or provide anything your accounts team needs.
Thanks,
[Your Name]
More Firm Past Due Invoice Reminder
If previous reminders have not received a response, you can become more direct without being rude.
Subject: Payment Required – Invoice #[Number]
Hi [Name],
This is a follow-up regarding Invoice #[Number] for [Amount], which was due on [Date] and is now [Number] days past due.
Please arrange payment by [Payment Date] or contact us as soon as possible if there is an issue with the invoice.
If you have already submitted payment, please send the payment confirmation so we can update our records.
Thank you,
[Your Name]
[Business Name]
Only include a specific payment deadline when it is appropriate for your business and consistent with your agreement with the customer.
What to Say on a Past Due Invoice
The most important thing is to be specific, polite, and action-oriented.
Instead of writing:
Please pay your invoice immediately.
Try:
Invoice #1042 for $1,250 was due on September 25 and remains unpaid. Please arrange payment or let us know if there is an issue preventing payment.
The second version gives the customer useful information and tells them exactly what needs to happen.
Avoid long explanations, emotional language, accusations, or threats. A professional payment reminder should focus on the invoice and the steps required to resolve it.
How to Send a Reminder for an Overdue Invoice
Start by checking your records before contacting the customer.
Confirm that the invoice was actually sent, the due date has passed, the payment has not already been received, and the amount shown is correct.
Then send a short email containing the invoice details and payment instructions. If possible, attach the original invoice or include a secure payment link so the customer does not have to search for it.
For businesses handling many invoices, automated reminders can reduce the amount of manual follow-up. Xero, for example, provides invoice reminder functionality that can be configured for invoices approaching or passing their due dates.
You can also create and manage invoices through the Invoice Generator when you need a straightforward way to prepare invoice documents.
How to Send a Reminder for an Unpaid Invoice Without Sounding Rude
The easiest way to remain professional is to focus on facts rather than blame.
Use phrases such as:
- “I’m following up regarding…”
- “Our records show that…”
- “We have not yet received payment…”
- “Please let us know if you need another copy…”
- “Could you confirm when payment is expected?”
- “If payment has already been sent, please disregard this message.”
Avoid phrases such as:
- “Why haven’t you paid?”
- “You are ignoring our invoices.”
- “Pay immediately or else.”
- “We have waited long enough.”
Your objective is to get the invoice paid, not to create an unnecessary conflict.
What If the Customer Says They Cannot Pay?
Sometimes an overdue invoice is not caused by an oversight.
A customer may have a temporary cash-flow problem, dispute part of the invoice, or be waiting for approval from their accounting department.
Ask what is preventing payment and determine whether the issue can be resolved. Depending on your business relationship and agreement, you might consider a payment arrangement rather than allowing the invoice to remain unanswered.
If you agree to different payment terms, put the agreement in writing. Stripe recommends documenting payment terms and any applicable late fees or consequences rather than relying on informal assumptions.
Should You Charge a Late Fee?
A late fee can encourage timely payment, but it should not be introduced unexpectedly.
If your contract or original invoice clearly established a late-payment fee, you can remind the customer about the applicable terms when the invoice becomes overdue.
For example:
As stated in our payment terms, a late fee may apply to balances remaining unpaid after the due date.
Do not add a new fee simply because an invoice is late unless you have a valid basis for doing so. The enforceability of late fees can depend on the agreement and applicable law.
How to Prevent Future Past Due Invoices
The best overdue invoice strategy is to reduce the number of invoices that become overdue in the first place.
State the exact due date
Do not make customers calculate when payment is due. Write the actual date on the invoice.
For example, use “Payment due October 15, 2026” instead of relying only on “Net 30.”
Clear payment terms can reduce confusion and make it easier for customers to process invoices.
Invoice promptly
Send the invoice soon after completing the work or delivering the product.
Waiting several days or weeks before invoicing delays the entire payment process.
Make payment easy
Provide clear payment instructions and, where appropriate, an online payment option.
A customer who can pay immediately from the invoice has fewer reasons to postpone payment.
Track outstanding invoices
Maintain a list showing each invoice, customer, amount, due date, and payment status.
You can divide invoices into categories such as:
| Status | Suggested action |
|---|---|
| Not yet due | Monitor |
| Due today | Send a friendly reminder |
| 1–7 days overdue | Send a polite follow-up |
| 8–30 days overdue | Send a firmer reminder |
| More than 30 days overdue | Review and escalate according to your terms |
The exact schedule should depend on your industry, customer relationships, contract terms, and the size of the outstanding balance.
Past Due Invoice Reminder Best Practices
Keep your reminder short. The customer should be able to understand the issue within a few seconds.
Always reference the invoice number and amount. This is particularly important when a customer has multiple unpaid invoices.
Include the original due date and make the requested action clear. If possible, provide a direct payment method or attach the invoice again.
Most importantly, follow up consistently. Xero notes that a structured process that begins with friendly reminders and gradually becomes more direct can help businesses pursue payment while preserving customer relationships.
Also see: Free Invoice Due Date Calculator
Frequently Asked Questions
How do I send a reminder for overdue invoices?
Send a short, professional email that identifies the invoice number, amount owed, original due date, and payment instructions. Start with a friendly reminder and become more direct if the customer does not respond.
It is also useful to ask whether there is an issue preventing payment. This can uncover missing invoices, billing errors, or approval problems.
What to say on a past due invoice?
State that the invoice is past due and provide the relevant details. For example: “Invoice #1042 for $1,250 was due on September 25 and remains unpaid. Please arrange payment at your earliest convenience, or contact us if there is an issue with the invoice.”
Avoid accusatory language. The goal is to make payment as easy as possible.
How do I send a reminder for an unpaid invoice?
First, verify that the invoice was sent and that payment has not already been received. Then send a reminder by email or another agreed communication channel with the invoice attached or a link to the original invoice.
If there is no response, follow up again according to a consistent schedule. For larger accounts or older debts, a phone call may help identify why payment has not been made.
How do I politely remind someone to pay an invoice?
Use neutral language that assumes the delay may be an oversight.
For example:
Hi [Name], I hope you’re doing well. I’m following up regarding Invoice #[Number] for [Amount], which was due on [Date]. We haven’t received payment yet, so I wanted to check whether you need anything from us to complete the payment. Thank you!
This is polite while still making the requested action clear.
Conclusion
A past due invoice reminder does not need to be complicated. The most effective messages identify the unpaid invoice, state the amount and due date, provide an easy way to pay, and give the customer an opportunity to explain any problem.
Start with a friendly reminder and gradually become more direct when an invoice remains unpaid. Keeping accurate records, setting clear payment terms, invoicing promptly, and using automated reminders can also reduce the amount of time you spend chasing outstanding payments.
For small businesses, timely follow-up matters because overdue invoices can tie up money that is needed for payroll, inventory, operating expenses, and growth. A consistent reminder process gives you a practical way to protect cash flow without unnecessarily damaging customer relationships.
Sources and further reading
- Xero – How to chase outstanding invoices and get paid faster — practical guidance on reminder timing, follow-ups, and overdue invoices.
- QuickBooks – 2026 Small Business Late Payments Report — current data on unpaid invoices and small-business cash-flow effects.
- Stripe – How to collect unpaid invoices — guidance on reminders, payment terms, and escalation.
- Stripe – How to strategically write and use an outstanding payment letter — useful information on what an overdue payment notice should contain.