Collection Letter Template for Overdue B2B Accounts

A collection letter template is a pre-written, formal written notice sent by mail (or as a PDF attachment) to a customer with an overdue invoice, used when a situation has escalated past routine email reminders or when a business needs a documented paper trail for later legal or collections action.

What Is a Collection Letter?

A collection letter is the more formal counterpart to a collection email. Where emails are fast, frequent, and used throughout the early stages of an overdue invoice, letters are typically reserved for accounts that have aged further, carry larger balances, or need a physical, signed record that can later support a collections agency referral or legal claim. Many B2B credit teams send collection letters by certified mail specifically so they have proof of delivery.

For the broader strategy behind when and how to escalate, see our guide to writing a dunning letter that gets paid. This page focuses on ready-to-use templates for each stage of that escalation.

When to Use a Letter Instead of an Email

Most AR teams don't start with a letter. A typical escalation path runs through several collection emails first, then moves to a letter once an account crosses a specific threshold, commonly 45 to 60 days past due, or once a customer has stopped responding to email outreach entirely. The formality of a mailed letter itself signals seriousness that an email can't fully replicate, which is part of why it works as an escalation tool rather than a first-line one.

5 Collection Letter Templates

Template 1: First Written Notice (30-45 Days Past Due)

[Date]
[Customer Name]
[Customer Address]

Re: Invoice [#] - Amount Due $[Amount]

Dear [Name],

Our records show Invoice [#], dated [Invoice Date] and due [Due Date], remains unpaid as of today. The outstanding balance is $[Amount].

If payment has already been sent, please disregard this notice. Otherwise, please remit payment within 10 business days, or contact us at [Phone/Email] to discuss the account.

Sincerely,
[Your Name], [Title]

Template 2: Second Notice (45-60 Days Past Due)

Dear [Name],

This is our second written notice regarding Invoice [#] for $[Amount], now [X] days past due. We have not received payment or a response to our prior notice dated [Date].

Please remit payment within 7 business days of this letter. If there is an issue with the invoice preventing payment, contact us immediately so we can resolve it. Continued non-payment may result in your account being placed on credit hold.

Sincerely,
[Your Name], [Title]

Template 3: Final Demand Letter (60-90 Days Past Due)

Dear [Name],

This letter serves as final demand for payment of Invoice [#] in the amount of $[Amount], now [X] days past due. Despite prior notices dated [Date] and [Date], this balance remains unpaid.

Unless we receive payment in full, or a signed payment plan agreement, within 10 business days of the date of this letter, we will refer this account to a third-party collections agency and may report this delinquency to commercial credit bureaus. We would prefer to resolve this directly and avoid that outcome. Please contact [Phone/Email] immediately.

Sincerely,
[Your Name], [Title], [Company]

Template 4: Pre-Legal Notice (90+ Days Past Due)

Dear [Name],

Despite repeated attempts to resolve the outstanding balance of $[Amount] on Invoice [#], now [X] days past due, we have not received payment or a satisfactory response.

This letter serves as notice that if payment in full is not received within [X] business days of the date of this letter, we will pursue all available remedies, which may include referral to legal counsel and filing a claim to recover the amount owed, along with applicable interest, fees, and costs of collection as permitted under our agreement and applicable law.

We remain willing to resolve this matter directly. Please contact [Phone/Email] without delay.

Sincerely,
[Your Name], [Title], [Company]

Template 5: Collections Agency Referral Notice

Dear [Name],

This letter confirms that your account balance of $[Amount] on Invoice [#], outstanding for [X] days, has been referred to [Collections Agency Name] for recovery, effective [Date].

All future communications regarding this balance should be directed to [Collections Agency Contact Information]. We are no longer able to accept payment on this account directly.

Sincerely,
[Your Name], [Title], [Company]

What to Include in Every Collection Letter

Regardless of which stage a letter is used at, a handful of elements should appear every time: the exact invoice number and amount, the original due date and current days past due, a clear deadline for the customer's response, and a direct phone number or email for the recipient to resolve the issue without friction. Letters that omit a hard deadline tend to get deprioritized by the recipient's accounts payable team the same way a vague email does.

Documenting the Paper Trail

One advantage of a letter over email is the stronger documentation it creates, particularly when sent by certified mail with return receipt. If an account ultimately goes to collections or legal action, having a dated, delivered sequence of written notices showing escalating seriousness materially strengthens the case. Credit teams that skip straight from silence to a collections referral, with no documented letter sequence in between, often weaken their own position unnecessarily.

Keeping the underlying payment behavior visible at the account level, not just at the invoice level, also helps decide when escalation to a letter is warranted in the first place. For the formula behind tracking that, see our DSO guide, and for the broader collections and dunning process this fits into, see our dunning process guide.

Frequently Asked Questions

What is a collection letter?

A collection letter is a formal written notice, typically sent by mail, requesting payment on an overdue invoice. It is used at later stages of the collection process than email, often when an account needs a documented paper trail for a potential collections or legal referral.

When should I send a collection letter instead of an email?

Most AR teams move from email to a letter once an account crosses roughly 45 to 60 days past due, or once a customer has stopped responding to email outreach entirely. The formality of a mailed letter signals seriousness that supports the next stage of escalation.

Should collection letters be sent by certified mail?

For later-stage letters, especially a final demand or pre-legal notice, certified mail with return receipt is common practice because it creates proof of delivery, which strengthens the case if the account is later referred to collections or legal counsel.

What should every collection letter include?

The invoice number and amount, the original due date and current days past due, a specific deadline for the customer to respond, and direct contact information for resolving the issue.

How many collection letters should be sent before referring to collections?

Most businesses send two to three escalating letters, a first notice, a second notice, and a final demand, before referring an account to a collections agency or legal counsel, typically once an account passes 90 days past due with no response.