How to Write a Letter Regarding an Unpaid Invoice/Debt: Example and Writing Tips

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What to Do When a Customer Fails to Pay?

When a customer fails to pay an invoice, start to send a friendly reminder to the customer that the invoice is overdue and ask them to pay as soon as possible. This is often a simple and effective solution. However, if the customer doesn’t respond to the initial reminder, follow up with them to find out why the payment hasn’t been made. It could be that there was a misunderstanding or a problem with the invoice.

Negotiate a payment plan: If the customer is having financial difficulties, you can try to negotiate a payment plan that works for both of you. This can help to keep the relationship with the customer positive and may also help you to get paid faster.

As a last resort, you can take legal action to collect the debt. However, this can be costly and time-consuming and may damage your relationship with the customer. You can also consider using a debt collection agency, they will handle the collection process on your behalf and they have legal authority to contact customers and negotiate payment.

How to Craft a Strong Overdue Payment Reminder Notice?

Writing a letter regarding an unpaid invoice or debt can be a delicate task, but it’s an important step in the process of getting paid. Here are some tips for writing an effective late payment notice:

  • Keep it Professional

    It’s important to maintain a professional, polite tone when writing the letter, regardless of the fact that the customer hasn’t paid. Use respectful language and avoid being confrontational. Additionally, make sure to address the customer by their correct name, as this adds a personal touch and shows respect. For example, start the letter by saying: "Dear Mr. Smith."

  • Use a Clear and Direct Subject Line

    The subject line of the letter should clearly indicate that it’s regarding an unpaid invoice or debt. This will help the customer understand what the content of the letter is right away. A good example of a subject line could be: "Reminder Regarding Unpaid Invoice No. XXXXX."

  • Include the Invoice Number and Amount

    Make sure to include the invoice number and the total amount that is due in the letter. This will help the customer identify which invoice is overdue, as well as how much they owe. For example, you could write: "The invoice number is XXXXX and the total amount due is $XXX.XX." Also, state the payment due date: "The original due date was XX/XX/XXXX and it is now XX/XX/XXXX."

  • Offer a Solution

    Suggest a solution that will help the customer pay the invoice, such as offering a payment plan or discussing alternative payment methods. For instance, you could write: "We are open to discussing flexible payment arrangements that will work for both of us. Please contact me at your earliest convenience so that we can find a solution."

You May Also be Interested in Our Sample Letter for Writing an Effective Bad Check Notice

Need to Write to Client for Overdue Bill Payment? Our Letter/ Email Templates

Invoice Late Payment: First Polite Reminder (7 days)

Dear Mrs. X,

We would like to bring to your attention that payment regarding invoice number: (XU-204850) is now overdue.

As a friendly reminder, our company policy is to provide our clients with (x days/x weeks etc.) after the last billing date to successfully complete a payment on time.

Our records show that your last payment is now (X days/months) overdue. We would kindly request and appreciate if this payment could be made as soon as possible.

Please do not hesitate to contact our customer service department should you have any questions or require further assistance with this matter.


(name + Job position/title)

Second Professional Reminder: Payment Plan Proposal (14 days)

Subject: Invoice #123456 - Unpaid Amount: $1000 - Second Reminder

Dear [Customer Name],

We are writing to follow up on our previous letter regarding invoice #123456, which has been overdue for payment since [original payment due date]. The total amount due is $1000.

We have not yet received payment for this invoice and we wanted to remind you that it is important to take care of this outstanding balance as soon as possible.

We understand that sometimes unexpected financial difficulties can arise, and we are willing to work with you to find a solution that works for all of us. We propose that we set up a payment plan for you to pay off the outstanding balance in a manageable way.

We would like to schedule a call or meeting with you to discuss the details of the payment plan. Please let us know when would be a convenient time for you and we can proceed with the payment plan.

Please note that if payment is not received within the next 10 days, we will have to take legal action to collect the debt.

Thank you for your attention to this matter. We look forward to hearing from you soon.


[Your Name]

Late Unpaid Bill: Final Notice Before Legal Action (30 days)

Dear (Name),

We are writing to inform you that this letter serves as a final notice before legal action regarding invoice number: (XIF 94750-34), which was due for payment on (date/month/year). Despite our previous reminder letters, the payment is now (X) months/days overdue.

We regret to inform you that (name of company) will be commencing legal proceedings against (name of late payment company) without further delay, for the recovery of all outstanding money owed, associated interest incurred to date, as well as any associated legal costs required for the case.

This is your final opportunity to pay the outstanding invoice before we proceed with legal action. We have enclosed one final copy of the invoice for your records.

Please contact us immediately on the phone number listed below to make arrangements to pay the outstanding balance.


(name, job position & direct Tel.No.)

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