You’ve generated an invoice using Kiwili’s invoicing tool, but it remains unanswered? It’s always tricky to follow up with a client in case of late payment. In our article on the 5 tips for action in case of late payment, we guide you on how to react when a client doesn’t pay their invoice on time. We specifically mention that the first thing you can do when an invoice remains unpaid after the prescribed deadline is to send a reminder email or letter. Drafting these communications can be a bit tedious, which is why we provide guidance on what information to include in your message and some writing tips. Finally, we’ll provide examples of reminder letters and emails, as well as formal notices.


How to Follow Up on an Unpaid Invoice, by Letter or Email?


  • The Letter: Note that if you typically communicate with your client via email, they might perceive this letter as a formal step, whereas their late payment could simply be due to oversight. The letter might be particularly suitable if you’ve already reminded your client about the due invoice over the phone.


  • The Email: Conversely, the client might not grasp the seriousness of the late payment via email. In this case, careful attention to wording is required to express your dissatisfaction while remaining courteous.


You can also send the account statement to your client. Start reminding your clients now with just a few clicks through Kiwili’s automated account statement sending.


What Information Should Be Included in Your Reminder Message?


Regardless of the message format you choose, certain elements must be included:


Invoice number

Amount due

Due date for payment

Your contact information (at the end of the email, or in the header for a letter)


Writing Tips for Your Reminder Letter for Unpaid Invoice


  • Even if the late payment annoys you, try not to let it show. Maintain a cordial yet firm tone to preserve a healthy business relationship. Also, don’t forget the polite phrases.
  • This is only the first reminder message, so don’t mention legal action immediately.
  • You can attach the unpaid invoice to the message.
  • Keep the message short and get straight to the point.
  • Pay attention to the subject line of your message: it should be short, precise, and include words like “late”, “invoice #XXXX”, or “reminder”. If the email or letter addresses different subjects, you should mention it in the subject line.


When to Schedule Follow-Ups for Unpaid Invoices?


Scheduling follow-ups for unpaid invoices is an important task for any business. Moreover, it can help you retrieve your money more quickly and avoid late payment penalties. To guide you in this process, follow these tips to establish an effective schedule for follow-ups on unpaid invoices.


First, you need to decide how often you’ll follow up on unpaid invoices. The most common frequency is twice a month, but you can also choose to do it monthly or weekly, depending on your needs.


Examples of Letters and Emails for Unpaid Invoices


Example Email Reminder for Late Payment


To: Recipient’s Email

Subject: Late Payment for Invoice #XXXX

Hello Mr./Ms. X,


As of today, you have not yet settled the payment for invoice #XXXX, amounting to X, which was due on dd/mm/yyyy for the services I provided to you.


I believe this may have simply slipped your mind.


Could you please arrange for payment as soon as possible?


Thank you in advance,




Example Reminder Letter for Late Payment


Your Company Name

Your Company Address

Postal Code / City

Phone Number

Client Company Name

Client Address

Attn: Mr. X

Postal Code / City



Subject: Late Payment for Invoice #XXXX


Dear Sir,


I have provided [mention the services provided] for you. As per our agreement, you were supposed to settle your invoice #XXXX amounting to X by dd/mm/yyyy.


However, to date, I have not received payment for this invoice. I believe this may have simply slipped your mind.


I kindly request that you settle this invoice as soon as possible.


Yours sincerely,


Sender’s Name



It’s possible that even after this message, your client still hasn’t paid their invoice. In this case, you can give them a call and wait for a reasonable period after this call. As a last resort, you can send them a formal notice with acknowledgment of receipt.


Example Courtesy Reminder Letter


A courtesy reminder letter is sent to inform a client that they have an outstanding debt and must settle it as soon as possible. The courtesy reminder letter is usually sent after the client has made several payment requests.


[Your Company Name]

[Your Company Address]

[Postal Code / City]

[Phone Number]

[Client Company Name]

[Client Address]

Attn: Mr./Ms./Mrs. [Last Name]

[Postal Code / City]


Subject: Courtesy Reminder


Dear [Mr./Ms./Mrs.] [Last Name],


I am writing to remind you that you have neglected to settle your invoice number [invoice number] for a total of [invoice amount]. According to our records, this invoice is now [number of days late] days overdue.


We hope that you have simply forgotten to settle it and that you will send your payment in the coming days. If you have any questions regarding your invoice or need assistance in settling your payment, please do not hesitate to contact us.


Best regards,


[Sender’s Name]



Example Formal Notice Letter, After No Response


[Your Company Name]

[Your Company Address]

[Postal Code / City]

[Phone Number]

[Client Company Name]

[Client Address]

Attn: Mr. X

[Postal Code / City]




Subject: Formal Notice for Payment of Invoice #XXXXX


Mr./Ms. [Last Name],


I have provided [mention the services provided] for you. As per our agreement, you were supposed to settle your invoice #XXXX amounting to X by (invoice due date). However, as this payment was not made in a timely manner, I sent you a first reminder letter on (date of first reminder letter). I also called you on (date of the call) to remind you of your obligations.


Yet, to date, we have not received payment for invoice #XXXXX.


Please be reminded that the amount of your debt is X (initial invoice amount + any late penalties).


However, as we also have our own commitments, we cannot wait any longer for this payment.


If we do not receive the amount due at our offices, by certified check made payable to (your name), within X days of receiving this notice, we will have no choice but to initiate legal proceedings against you, without further notice or delay.


We sincerely hope not to have to take such action.


Yours faithfully,


[Your Name]



Late Payment: What to Do Next?


If all your follow-up attempts go unanswered, you don’t have many options left. We’ll tell you more about the actions you can take in our article “Late Payment on a Client Invoice: 5 Action Tips”.


For French companies, you can refer to the official website of the public service.

For Quebec companies, you can consult the official website of the Ministry of Labor.

Unfortunately, supplier-client relationships are not always simple. However, Kiwili can help you manage your client relationship, as it is also a CRM software.


We invite you to discover our article on the basic rules to get paid quickly.