Dunning Letter: Meaning & Templates to Get Paid on Time

A dunning letter is a formal written notice asking a customer to pay an overdue invoice, usually sent 20 to 30 days past the due date once reminder emails and phone calls have gone unanswered. Most B2B finance teams send three or four dunning letters, each firmer than the last, before escalating to legal action. It marks a specific escalation point in the accounts receivable process, where the situation now requires something more formal.

Getting this right matters. A poorly written dunning letter either fails to prompt payment or damages a client relationship that might otherwise be salvageable. A well-structured one recovers the debt while leaving the door open for the relationship to continue. This guide covers:

• What Is a Dunning Letter (or Dunning Notice)?
• What Does the Dunning Process Look Like?
• Dunning Email vs Dunning Letter
• Things to Include in a Dunning Letter
• Our Dunning Letter Templates
• How Do You Automate Dunning Letters?
• How to Avoid the Need for a Dunning Letter

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What Is a Dunning Letter (or Dunning Notice)?

A dunning letter, also called a dunning notice, is a formal written communication sent to a customer with an overdue or past due invoice. Its purpose is to remind the customer of the outstanding balance, convey a sense of urgency and clearly ask for the amount to be paid promptly.

Unlike email payment reminders, dunning letters mark a more serious phase in the accounts receivable process. They’re usually sent once initial emails or phone calls haven’t led to payment, and they make clear that the debt needs to be settled to avoid consequences such as late fees, restricted services or legal action.

What Does “Dunning” Mean?

“Dunning” comes from the verb to dun, which means to repeatedly ask someone to pay a debt. In business, the dunning process is the structured sequence of reminders a company sends to collect overdue payments, from a friendly email before the due date to formal letters and, as a last resort, a legal notice.

Dunning letters are one part of that process. They come after the early reminders, once the conversation needs to become more formal.

Dunning Notice vs Dunning Letter vs Final Demand

In most businesses, “dunning notice” and “dunning letter” mean the same thing, and the two terms are used interchangeably. Some companies use “notice” for earlier, often digital reminders, such as automated past due notices, and keep “letter” for more formal written communication, but there’s no universal standard.

The real difference is with a final demand, sometimes called a demand letter. It’s the last formal step before legal action or handing the account to a collection agency.

Whatever you call it, what matters is the content: clear invoice details, a specific payment deadline and the right tone for the stage of the process. Dunning letters work much like a collection letter, and templates #3 and #4 below cover the final demand stage.

What Does the Dunning Process Look Like?

A typical dunning process moves from friendly reminders to formal letters as an invoice ages, with each step a little firmer than the last. Most B2B finance teams follow a sequence like this:

The process starts before the invoice is even due, with a friendly reminder a few days ahead and another on the due date itself. Once the due date has passed, the first reminders should stay polite, assuming the delay may be unintentional. The goal at this stage is to prompt payment while keeping a positive customer relationship.

If there’s no response, the follow-ups become more assertive, by email or SMS. By the third reminder, it’s usually time for collection calls, which allow for direct conversation and quicker resolution, and show the customer that the payment, and the relationship, matter to you.

When emails and calls don’t secure payment, formal dunning letters come next. They signal a higher level of urgency and make clear that further delays may lead to more serious action. A legal notice is the final step, and should only be used once every reasonable attempt to collect has been made.

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When Should You Send a Dunning Letter?

Send your first dunning letter once an invoice is about 20 to 30 days past due, and only after several reminder emails and at least one phone call have gone unanswered. Space each following letter 5 to 10 business days apart, so the customer has time to respond before the next step.

The exact timing depends on your payment terms and the customer. On net 60 terms, or for a long-standing customer with a good payment history, you might wait a little longer. For a new customer or one with a history of late payments, you might move to formal letters sooner. Whatever timing you choose, apply it consistently, so every overdue invoice follows the same escalation path.

Dunning Email vs Dunning Letter

Both are part of a structured dunning strategy, but they serve different stages of the collections process and carry different weight with the recipient.

A dunning email is sent earlier in the escalation sequence, typically before or shortly after an invoice becomes overdue. The tone is lighter, the format is digital, and the aim is to prompt payment before the situation becomes formal. Payment reminder emails land in a billing contact’s inbox alongside dozens of other messages, so they’re easy to act on quickly, but also easy to deprioritize.

A dunning letter is a formal written document, sent when emails and phone calls have already gone unanswered. It signals that the matter has escalated beyond routine follow-up. Receiving a formal letter carries more weight than another email, which is exactly why it tends to prompt action when earlier reminders haven’t.

The practical difference for your AR process is timing and channel. Emails handle the early and mid-stage reminders. Letters come in once those efforts have been exhausted, and the goal shifts from gentle follow-up to formally documenting the debt and your attempts to collect it.

One thing both formats share: the more personalized they are, the better they work. Generic mass messages, whether email or letter, get treated as spam. A message that references the specific invoice number, the exact amount, and the customer’s name and company performs much better on either channel.

Things to Include in a Dunning Letter

While drafting an effective dunning letter, it’s essential to include specific details that encourage payment while maintaining a professional tone. Here’s a breakdown of key elements:

1. Recipient’s Information: Address the letter to the appropriate individual by including their full name, title, and company name. Adding details about your provided services or products serves as a reminder of the relationship and reinforces the value you’ve delivered.
2. Your Contact Information: Offer multiple ways for the recipient to get in touch. List your business address, email, and phone number to make it simple for them to resolve the payment issue or ask questions. The easier it is to contact you, the more likely they’ll address the payment promptly.
3. Overdue Invoice Attachments: Attach copies of all overdue invoices to provide the recipient with clear visibility into what’s owed. This should include invoice numbers, amounts, and due dates, with a summary of these details in the body of the letter. A concise list helps avoid confusion, especially if multiple invoices are outstanding.
4. Invoice Details and Payment Deadlines: Reference the specific invoice numbers, the total amount due, and the days past due to underscore the urgency. Reinforcing these details emphasizes missed deadlines and can motivate the client to act quickly.
5. Available Payment Options: Clearly list payment methods such as credit card, bank transfer, or online payment options. Make payment as easy as possible by providing direct payment links if available. The more straightforward the process, the quicker you’re likely to receive payment.
6. Consequences of Continued Non-Payment: Outline potential next steps if the debt remains unpaid, such as suspension of services, assignment to a collection agency, or legal action. Refer to any contractual clauses that back these actions, like late fees or penalties, while maintaining a respectful, professional tone. This demonstrates the importance of payment without damaging the client relationship.

Our Dunning Letter Templates

Using a structured, phased approach to dunning letters can significantly improve payment recovery rates while maintaining strong client relationships. Below, we provide four dunning letter templates that escalate from a friendly reminder to a final legal notice, guiding the process and helping ensure timely collection of outstanding payments.

Template #1: Gentle Reminder for Payment

The first dunning letter is a courteous reminder, typically sent after initial emails or phone calls haven’t resolved the overdue payment. It summarizes the outstanding invoice, includes payment methods and gently encourages the client to address the balance.

Here’s a copy-paste version:

Template #2: Notice of Impending Service Restriction

This second dunning letter escalates the tone, explaining that access to your services or products may be limited if payment isn’t made within a set timeframe. It stresses the importance of paying on time, without yet taking restrictive action.

Copy and adapt this version:

Template #3: Service Restriction and Legal Warning

At this stage, the letter tells the client their access has been restricted due to non-payment, and gives a clear warning of legal consequences if payment isn’t made within a set period. The tone is more direct and signals how serious the situation has become.

Use this text as your starting point:

Template #4: Legal Notice Due to Non-Payment

This final template is used once all previous reminders have been exhausted and legal action has started. It tells the client the debt is now in legal proceedings and urges them to settle the balance to avoid further penalties or costs. Requirements for legal notices vary by country and state, so check with your legal counsel before sending it.

Copy the full letter below:

How Do You Automate Dunning Letters?

You automate dunning letters by setting up a workflow that sends each reminder, notice and letter at the right point after the due date, using invoice data from your ERP or accounting system. Once it’s in place, every overdue invoice follows the same escalation path, and reminders stop as soon as the customer pays.

Most ERPs offer some dunning on their own. NetSuite can generate dunning letters based on how many days an invoice is overdue, and QuickBooks can send automatic invoice reminders. These work for simple cases, but they tend to follow fixed schedules, focus on one channel, and leave finance to track replies, disputes and promises to pay elsewhere, which is usually the point where teams start to outgrown these features and need a dedicated AR platform.

Dedicated accounts receivable automation goes further. A good dunning workflow should:

• Combine channels in one sequence, with emails and SMS for early reminders, phone call tasks for escalation, and formal letters and past due notices for the later stages.
• Adapt to each customer, with different sequences for different segments, such as a softer approach for key accounts and earlier escalation for repeat late payers.
• Pause when it should, for example while a dispute is being resolved or after a customer promises to pay, so nobody gets chased for an invoice they’re already dealing with.
• Log every step, so if an account does reach a final demand or legal action, there’s a clear record of every attempt to collect.

How Upflow Automates Dunning

In Upflow Collections, dunning workflows run on invoice data synced from your ERP or accounting system. Each action is triggered by a delay you set from the invoice’s issue or due date, so a workflow can start with reminders before the due date and step up to firmer emails, calls and letters as the invoice ages. Smart Rules assign the right workflow to each invoice automatically based on conditions you define, and collection is paused when a customer disputes an invoice or makes a promise to pay.

AI collection agents, part of Upflow Intelligence, handle what comes back. When a customer replies to a reminder or dunning letter, the agent can draft or send a response, log a promise to pay or raise a dispute from the email, and capture remittance advice so the payment is applied to the right invoices. Once a promise to pay is logged, reminders for that customer pause automatically. You choose how much each skill does on its own, from suggestions your team reviews to fully automatic, and when the agent isn’t confident, it leaves the decision to your team. Every reminder, letter and reply is logged in the customer’s timeline, where finance, sales and customer success can all see it.

How to Avoid the Need for a Dunning Letter

The best dunning letter is the one you never have to send. These habits reduce late payments before they reach the formal stage:

1. Establish clear payment terms. Set precise payment terms in your contracts, including due dates, accepted payment methods and late fees. Clear terms help customers understand their obligations from the start.
2. Send proactive payment reminders. Schedule friendly reminders before invoices are due. Automating them keeps payments top of mind for customers, without your team having to follow up by hand.
3. Offer multiple payment options. Make paying easy with a choice of methods, such as bank transfers, cards or an online payment system. The more convenient it is, the fewer delays you’ll see.
4. Incentivize early payment. Small discounts for paying early give customers a reason to prioritize your invoices.
5. Automate invoicing and payment tracking. Send invoices automatically and track payments in real time, so you can act as soon as an invoice is close to becoming overdue. A regularly reviewed aging report shows which accounts need attention first.
6. Segment customers by payment behavior. Group customers by their payment history, so you can give extra attention to those who often pay late and keep communication simple for everyone else.