How to Write Overdue Invoice Letters

Overdue invoices are a serious problem for many companies. You must have a smooth cash flow alongside your daily operations. Your entire business depends on receiving payments on time.

Most businesses are uncomfortable with confronting clients about outstanding invoices. They might not want to damage their relationships with them. However, it is essential to know how to deal with such situations. Here, your best bet is to send regular past-due invoice letters.

For that, you should know how to write an overdue invoice letter. Your letters should be professional and friendly. But they should also be firm enough to get your message across properly. There are certain things to keep in mind when writing such sensitive letters that we will learn further.

In this blog, we will discuss various ways to get paid faster. We have also included many past-due invoice letter templates for your reference.

You cannot use the same writing style and tone in every overdue invoice collection letter. Tailoring your language is important. It ensures that you are emphasizing your message properly.

So, how to write past-due invoice letters?

Well, the answer is simple- A letter written after 15 days past the due date is surely different from one written after 60 days. You should adjust your writing tone accordingly depending on the number of days and the situation.

At times, clients reach out to you with a reason for non-payment. But, some clients stop responding to your texts and calls when their invoices become overdue.

Let us now find out how you can tailor your words and get paid faster.

1-15 Days Past Due

You should be extremely gentle and polite while sending a past-due payment letter for the first time. Use a friendly tone and let customers know that this is just a reminder. This letter should not sound like a warning.

• Your motive should be to preserve your relationship with clients.
• Explain the payment terms and guide them on how to pay.
• You can also ask them to acknowledge your letter by responding to it.
• Once the customer receives the letter, you can also call them up.
• It is necessary to talk to them personally at least once.

30-60 Days Past Due

Ask your accounts team to send another overdue payment letter after 30 days. The letter should be professionally drafted, but do not forget to maintain a courteous tone. Try to emphasize the urgency of the matter.

• Attach a copy of the invoice. Mention that you had sent the invoice along with payment overdue letters earlier but didn’t receive any response to date.
• Use sentences like “Please complete the payment at the earliest” and “We need your urgent attention to this situation.”
• Include the revised amount inclusive of the late fees.
• At this payment collection stage, you should not shy away from asking for the payment firmly.

90+ Days Past Due

If a client delays payment for a long time, it is less likely that they will pay at all. Hence, you should keep up with your follow-up overdue invoice letters.

• A letter sent after 90+ days past the due date is a warning.
• It gives clients a final chance to complete the payment.
• Let clients know that you are expecting payment within a certain number of days.
• If the payment is still outstanding, you have the right to take legal action against them. Thus, your final letter should inform clients about the same.

Charge Late Penalties

It is common for banks and financial institutions to impose late payment charges. They do so by imposing interest on all missed credit card bills and EMI payments. You can also charge a late payment fee on your overdue accounts.

• Discuss the penalties and related charges with your customers beforehand, or else do not mention them in the invoice and letters. If these things aren’t discussed earlier, you cannot charge any penalties.
• Any additional fees included without their knowledge can sour your company-client relationships.
• However, companies must refrain from charging any amount at their discretion. It should be a reasonable amount, mostly a certain percentage of the total due, say 7-10%.

Also, go through your state laws regarding how much interest you can charge annually. If your state allows you to charge 15% annually, you can divide that amount into 12 and charge monthly. A 15% interest charged annually equals 1.25% interest per month.

Additionally, you can enforce late payment fees as a way to get paid. Start adding up these fees to your invoice after the due date. It can set an excellent precedent. This way, your clients can learn that you expect to be paid on time.

The more the payments are delayed, the more the late payment charges. This fact can encourage clients to pay you at the earliest possible so that they don’t pay anything extra.

However, you cannot charge late penalties to all clients. Some clients fail to complete payments due to genuine reasons. They may not have received your letters and are hence, unaware of the matter.

Before taking any further steps, try to get in touch with them through several channels.

Offer Discounts and Payment Plans

They say- something is better than nothing. You might have to incentivize clients to pay you.

Some businesses offer early payment discounts to several customers. They ask their customers to pay before the due date in exchange for a good discount.

You can offer a small discount of 2-4% to attract early payments. This small percentage may not be very convincing, but it can surely work for some customers. Companies that are focused on cost savings are likely to avail of your discount offer.

These offers are regarding early payments.

What if your client has not paid you even after the due date?

You can try offering them a payment plan. An article published on Entrepreneur’s website suggests offering payment plans to clients with overdue accounts.

• You can divide the total amount receivable into smaller parts.
• Ask clients to pay a part every month.
• This way, they can pay off their debt over some time.
• It is also beneficial to you as you can regulate your cash flow.

This plan can also work for clients that reach out to you and ask for certain concessions. You can help them pay you by offering such payment plans.

Use a Polite Tone

Always be humble and polite while addressing a past-due payment letter. Being courteous helps you to maintain a good brand image and goodwill. This further strengthens your relationships with the customers in a better way. Together, it all will eventually lead to high customer retention and increased sales.

Clients are likely to ignore letters that are written in a rude tone. Moreover, such letters can affect company-client relationships negatively. But, if you use a polite tone, it can help you get paid faster and retain customers.

FreshBooks stated that invoices containing polite phrases like “thank you” and “please” are 5% more likely to be honoured.

Use sentences like:

• Thank you for your cooperation and time
• Please complete the payment within X days

Such phrases show your company in a good light and encourage clients to have a long-term relationship with you.

Automate Payment Reminders

Remembering due dates and sending payment reminders manually is a huge deal. So, you can rather take the help of your invoicing software.

Automate printing and mailing overdue invoice collection letters. PostGrid’s automated direct mail API can integrate into your invoicing software and help you print and mail invoices effortlessly.

Also, if you do not know how to write a letter for overdue payments, try using PostGrid’s pre-built templates.

You can set reminders on your invoicing software to send outstanding invoice letters. The ideal time plan is 1, 15, 30, 45, 60, and 90 days past due (just as we mentioned above). The software can send an automated email and mailpiece to clients on each of these days. You need not remember any dates or do anything manually.

The software can also add late penalties to the invoice amount automatically.

Get Help

If your invoices go unpaid even after 90 days, send a final unpaid invoice letter to your client. You need to mention that your next step involves a collection agency.

In case the payment is not completed within the specified time, you can take the desired action.

Your first option is to hand over the invoice to a debt collection agency, as you mentioned in the letter. It may take a while to get the payment process completed.

If this option does not work, you can take your clients to court. However, consider whether the invoice amount is worth taking so much effort. Sometimes, the cost of hiring a lawyer and the court fees exceed the amount of the unpaid invoice.

In Canada, it is quite easy to get your lawsuit to a small claims court. You only have to pay the court fees.

If your invoice amount is less than the state’s maximum limit, you need not hire a lawyer as well. Thus, you can take legal action against non-payers without spending a lot.

Tips for Writing a Past Due Invoice Letter

Below are some tips that can help you write professional and effective past-due invoice collection letters:

• For invoices overdue by a few days, include the words “for your ease” or “for your convenience”. You can draft your sentences as “For your convenience, I am attaching invoice #770 that was due 2 days back.”
• Always add links to complete the payment. Don’t forget to attach the main invoice.
• Use polite phrases such as kindly, please, requesting you, thank you, we appreciate, etc.
• Remind your customers of all the previous interactions you had with them. Prefer adding words like “As we discussed earlier,” “As you know,” or “As discussed on call the other day.” These statements can remind clients of your conversations regarding the payment terms.
• Also, use phrases that demonstrate urgency. “Immediate attention”, “urgent matter,” and “action required” are some examples of such phrases. If you are sending an email, use such phrases in your subject line.
• Skip the irrelevant details and talk to the point. You need not beat around the bush for a long time before coming to the main subject. It can lead to distraction from the issue.
• Notify customers that you are going to get in touch with them via phone. They should know that you intend to talk to them personally on the subject. Some customers are uncomfortable talking about these things. So, they would rather prefer to complete the payment before that happens.
• Run credit checks on high-ticket clients. If you are dealing with someone for the first time, it is advisable to learn their business history. You should only deal with reputable clients that do not delay payments unnecessarily.

It is not necessary to draft a unique past-due invoice letter for every client. You can use a common template for the same. These templates are already drafted for you, so you don’t need to worry about their format.

Such overdue invoice letter templates help save a lot of time and effort. You can edit the necessary fields. Using these templates, you can sound professional while staying focused on your objectives.

But you need to use a different tone for every letter. Hence, we have included a past-due invoice letter template to give you a clear idea. You can use this template for all clients at all stages, irrespective of the days past due.

Past Due Invoice Letter Template

[Your Full Name]

[Your Company Name]

[Company Details] (such as address and contact details)

[Date]

[Customer’s Full Name]

[Customer’s Company Name] (if applicable)

[Company Details] (if applicable)

Dear [Customer First Name]

[Opening Paragraph]. (Explain the main purpose behind your letter and pave the way for further details. Keep it soft and humble. This paragraph should be a mere reminder to reinforce all your previous conversations.)

[Invoice Details]. (Mention the invoice number, date, and particulars.)

[Late Fees]. (Include the amount of late fees charged and also write how you calculated the interest rate.)

[Payment Details] (Mention your bank account details for customers to pay you. You can also mention the other payment options available.)

[Closing Paragraph]. (Inform your customers that you have attached the invoice with the letter. Also, include your contact information and ask them to reach out in case of queries.)

Thank you for your time and cooperation!

Sincerely,

[Your Signature]

[Your Name and Designation]

Enclosed: Invoice No. [#]

You can edit and use this template for invoices that are past due by 1-15 days, 30-60 days, and 90+ days. You can change the tone and the choice of words according to your requirements.

We have put together two samples that you can send before the invoice becomes overdue. These early invoice letters can help you avoid late payments in the first place.

Below are some samples of invoice reminders and past-due payment letters that you can refer to:

Payment Reminder: 1 Week Before the Due Date

Hayley Collins

Galaxy Rentals 

Montreal, QC 

12th August 2025.

To,

Desmond Hopkins

Hi Mr. Desmond,

Hope you are having a great day. This letter is in regard to your invoice no. 856 generated on the 20th of July, 2025. We wish to remind you that this invoice will be due next week on the 26th of July, 2025. A copy of the invoice is attached.

We understand that you are busy, but we would appreciate it if you take the time to acknowledge the invoice.

Please contact us if you have any doubts or questions.

Thank you!

Best,

Hayley Collins

Accounts Department – Galaxy Rentals.

Enclosures: 1 (Invoice no. 856)

Why this reminder is effective: Your invoice due date is yet to come. Therefore, there is no need to bother the customer too much. This letter should be a reminder to aid in faster payments. Keep it short, informative, and friendly. You should also not ask for the payment directly, as the invoice is not due yet.

The reminder gives out a message to customers that you track your invoices regularly. And, you expect the payment on time.

Payment Reminder 2: On the Due Date

Alfie Parker

Canada Foods Network Pvt. Ltd.

12th August 2025.

To,

Summer Havens

Havens Apparels

Hello Summer,

I hope you are doing well! This is to remind you that your invoice #1900 is due today. The invoice was both emailed and mailed to you earlier. For your ease, we have attached a copy.

You can pay via debit card/credit card/net banking on our website. You can also send a check to the below address:

Canada Foods Network Pvt. Ltd.

10-123 1/2 MAIN STREET NW 

MONTREAL, QC 

We would be happy to assist you in case of any doubts.

Thank You,

Alfie Parker.

Sr. Manager – Operations.

Why this reminder is effective: Reaching out to clients on the due date can get you paid easily. This way, you won’t have to write any late payment invoice letters.

When you follow up regularly, clients feel the need to complete payments as soon as possible. Hence, you are likely to receive the payment on the same day or at least a few days later.

The invoice isn’t overdue yet, so be polite. It should be highly professional and humble.

1-15 Days Past Due Invoice Letter

Keith Wesley

Elite Media Inc.

Brampton, Ontario

12th August 2025

Steve Galecki

Star Construction Pvt. Ltd.

Dear Mr. Steve,

Hope you are doing well! This letter is in regard to your overdue invoice. As per our records, the due date was 5th August 2025.

Please find below the invoice details:

Date: 5th May 2025

Invoice no. 5284

Amount: $2,500

Particulars: 3 magazine advertisements from 1st January to 30th April 2025

As discussed earlier, the payment terms are 3 months from the issue date. Any payments completed beyond the due date are subject to a 5% interest charge. Requesting you to please look into the matter.

You can send a check to the address mentioned on the letterhead. Also, you can pay through net banking/debit card/credit card on our website.

In case of any questions or clarifications, please do not hesitate to reach out. You can drop me an email at keith@elitemedia.com.

We would like to thank you for your time and cooperation!

Sincerely,

[Your Signature]

Keith Wesley, VP – Sales and Marketing.

30-60 Days Past Due Invoice Letter

Phoebe Scott

Zing International

12th August 2025.

To,

Richard Valdes.

123 Main St.

Montreal, QC H3Z 2YZ

Dear Mr. Richard,

This is in regard to your invoice no. 770J. It was due on 1st July 2025, and we are yet to receive the payment. We had earlier sent an overdue payment letter on 15th July 2025 but did not get any response. Since it has been 42 days past the due date, we need your urgent attention to this situation.

As mentioned in the invoice, past-due amounts are subject to an interest of @15%. Hence, your total invoice amount is now $4,410. We have attached a copy of the invoice for your perusal.

You can complete the payment by logging into our website. There are several payment options available for your convenience. Otherwise, you can send us a check written to “Zing International Companies.”

Please complete the payment for the said invoice at the earliest. Feel free to contact us at (485) XXX-XXXX for any clarifications.

We thank you for your business and look forward to working with you again!

Regards,

Phoebe Scott

Sr. Sales Manager – Zing International, CA.

Enclosed: Invoice No. 770J

90+ Days Past Due

Michael Steffanina

Ace Interiors 

123 Main Street Rd.

Montreal, QC H3Z 2Y7 

12th August 2025.

Christian Auden

Pittsburgh, OH 15295

Dear Mr. Christian,

We are writing this letter to inform you that your invoice is now 105 days overdue. Our accounts team sent you two outstanding invoice letters on 10th June 2025 and 12th July 2025. But we didn’t hear back from you. We need your urgent attention to the matter.

This is our last unpaid invoice letter to you. Kindly remit the amount within 7 business days. Failure to do so will result in legal action. Please find the invoice details below:

Invoice Number: 10692

Date: 1st April 2025

Due Date: 29th April 2025

Current Amount Due: $47,940

As written in our contract, a late payment fee of 4% per month is chargeable. Please reply to this letter or drop me an email regarding when we can expect your payment.

You can transfer the full amount to the bank details written below:

Account Name: Ace Interiors 

Account Number: xxxxx xxxxx xx853

ABA Number: xxxxxx298

Bank Name: Bank of Canada 

Address: Wellington, Ottawa.

We have attached the invoice with this letter for your reference. Please get in touch with us as soon as possible.

Sincerely,

[Your Signature]

Michael Steffanina

Vice President, Marketing.

Enclosed: Invoice No. 10692

You can use these templates if you don’t know how to write a letter for overdue payments. Feel free to customize them according to your needs. You can also automate the process to save time and the effort needed to write such letters. Using PostGrid’s print and mail API, you can draft professional letters effortlessly.

Our API can help you pull details from your CRM and draft past-due invoice letters in seconds.

How to Draft Overdue Invoice Emails

Now that you know how to write a past-due invoice letter, it is worth knowing how to draft emails.

You can mix and match while using emails and physical letters for overdue payments.

For example,

• You can email an invoice copy immediately after generating it.
• Next, you can send another email one week before the payment is due.
• On the due date, you can send a physical letter to customers.
• Some companies prefer sending emails and mail at the same time for added effect.

Reaching out to clients through various channels is important. This way, you know that they are receiving your messages.

For sending emails, you should have your customers’ email addresses. Don’t forget to collect such information right at the beginning.

You can use the same letter samples mentioned above as email templates. The only difference is the subject line.

Find below some examples of subject lines used in overdue invoice collection letters:

• Follow-up on bill #5620
• Invoice no. 0721 is due today
• Invoice no. 250: Third reminder for payment completion
• Last warning for payment collection (Invoice #8609)

The subject line summarizes your emails and talks about the urgency of the situation.

What Are the Different Types of Invoices You Should Know About

A sales invoice is a document that informs customers about their transactions. It includes several other details like the:

• Seller Name
• Transaction Date
• Amount
• Payment Terms
• Particulars

Invoices streamline payment collections for small businesses. And they act as a reference for customers.

There are different types of invoices that you should be aware of. They are used in different situations and periods; they are:

Proforma Invoice

This type of invoice is drafted before the order gets placed. At this point, the customer is still in the decision-making phase. Your proforma invoice can help them decide whether they want to purchase from you.

It is similar to a regular invoice and provides all the necessary information. Some businesses refer to it as a quotation. Since the purchase has not yet been completed, there is no official entry in your accounts books for the same.

Companies need to draft such invoices with utmost care. Consider your interactions with the customer regarding the deal. You can include all the agreed terms and conditions in this invoice.

Standard Invoice

Standard invoices are also called purchase invoices. These invoices are generated once the order is completed. In the case of businesses selling products, the invoice is sent along with the delivery of goods. Other companies can send an invoice after the customer has paid for your services.

It is useful in collecting payments. Usually, invoices confirm the completion of sales. They inform the buyer about the transaction particulars like the due date and amount. Such standard invoices create an obligation for the customers to pay you.

Whenever an invoice is generated, an entry is made in the books of accounts of both the buyer and seller.

It is crucial to draft accurate invoices. All your past-due invoice collection letters are based on these invoices. Any mistake in the invoice can lead to customers refusing to pay.

Recurring Invoices

Recurring invoices are drafted for recurring purchases. For example, you own a plastic manufacturing company. You will draft recurring invoices for clients who need to purchase from you regularly. It could be weekly, monthly, or even half-yearly.

Similarly, consider that you are a magazine publication. If a client wants to book a space in your 6 upcoming issues, you will draft separate invoices for each issue. Sometimes, you can also draft a single invoice for all 6 issues. It is a subjective matter and depends on your discussions with the clients.

Your account team should be proactive about recurring invoices. Arrange to send invoices regularly. In the meanwhile, don’t forget to follow up with clients to complete payments.

Sending payment reminder letters along with recurring invoices is a good practice.

Over to You

Overdue invoices can make it difficult for you to keep your calm. But remember, your clients are probably distracted by several things. They might have an overflowing inbox wherein it is easy for your emails to get lost.

You can get paid easily by following the tips and templates mentioned above.

For added attention, consider sending your overdue invoice letters through the mail. 

PostGrid can help you draft, print, and mail your letters effortlessly. Thus, you can save a lot of time, resources, and effort while maintaining a steady accounts receivable account.