# What is dunning? > Dunning is the process of reminding customers about overdue payments, getting firmer as invoices age. How to set tone stages and let AI draft each one. Source: https://learn.ynteractive.com/content/glossary/dunning · Updated 2026-10-01 · Free from Stepthrough (https://learn.ynteractive.com) [Business](https://learn.ynteractive.com/content/glossary#topic-business) · [AI glossary](https://learn.ynteractive.com/content/glossary) Updated October 1, 2026 · By [Robert Breen](https://learn.ynteractive.com/content/about) Dunning is the process of contacting customers about overdue payments in a planned sequence: a friendly note first, then clearer and firmer reminders as the invoice gets older. The goal is to get paid while keeping the customer relationship intact. ## Why it matters for a small business Most small businesses chase late payments by feel: nothing for weeks, then an awkward email when cash is tight. A written dunning sequence fixes both problems. Everyone knows when a reminder goes out and how firm it should be, and customers get a consistent experience instead of silence followed by a surprise. The tone at each stage is the hard part, and it is where generic AI fails badly. Ask for "a payment reminder" with no rules and you can get threats, all caps and invented late fees, the kind of email that loses a client over a few hundred dollars. AI is useful here only when you give it your stages, your banned phrases and the point where a person takes over. ## In a real lesson: Build a Custom GPT That Writes Overdue Invoice Reminders In the [Overdue Invoice Reminders lesson](https://learn.ynteractive.com/content/custom-gpt-payment-reminder-emails-overdue-invoices), the bare prompt about an $850 invoice 45 days overdue gets a reply with all caps, emojis and threats of collections and legal action. Then you build the **Payment Reminder Writer** GPT for Maple Street Bookkeeping, a made-up firm, and its instructions contain a complete dunning ladder under "TONE BY DAYS OVERDUE": 1 to 15 days is a friendly note that assumes they missed it. 16 to 30 days is a clear reminder asking them to pay or reply with a date. 31 to 60 days is polite and firm, asking for payment within 7 days and offering a short call or a payment plan. At 61 days or more the GPT does not write the email and says the owner handles it personally. Other rules close the gaps: never say "final warning," "or else" or "legal action," never invent fees or interest, and never mention collection agencies, credit reports or lawyers. When you send the same test prompt again, 45 days overdue falls in the 31 to 60 day stage, so the rules call for a polite, firm reminder with the invoice details, ways to pay and one next step. [Try this lesson free](https://learn.ynteractive.com/modules/chatgpt-custom-gpt-finance) or [read the step-by-step guide](https://learn.ynteractive.com/content/custom-gpt-payment-reminder-emails-overdue-invoices). ## Common confusions ### Dunning vs collections Dunning is your own reminders to a customer. Collections usually means escalating an unpaid debt, sometimes to an outside agency, which has its own rules. The lesson's GPT stops before that point on purpose and hands off to the owner. ### Dunning vs accounts receivable [Accounts receivable](https://learn.ynteractive.com/content/glossary/accounts-receivable) is what you are owed. Dunning is what you do about the part of it that is late. ## Tips - Write your stages down with day ranges, and put them in the AI's instructions word for word. - Decide the stage where a person takes over, and make the AI refuse past it. - Keep a log of what was sent and when, so the next reminder is the right stage. ## Related terms [Accounts receivable](https://learn.ynteractive.com/content/glossary/accounts-receivable) · [Custom GPT](https://learn.ynteractive.com/content/glossary/custom-gpt) · [GPT instructions](https://learn.ynteractive.com/content/glossary/gpt-instructions) · [Prompt constraints](https://learn.ynteractive.com/content/glossary/prompt-constraints) · [Follow-up email](https://learn.ynteractive.com/content/glossary/follow-up-email) ## Where you use it: free lessons - [Build a Custom GPT That Writes Overdue Invoice Reminders](https://learn.ynteractive.com/content/custom-gpt-payment-reminder-emails-overdue-invoices) (ChatGPT, 8 min) ## More free tutorials [AI for Finance](https://learn.ynteractive.com/content/industry/finance) ## Prompt templates that use it [Declined card notice prompt](https://learn.ynteractive.com/content/prompts/card-declined-notice-prompt) · [Final notice for an overdue invoice prompt](https://learn.ynteractive.com/content/prompts/final-notice-overdue-invoice-prompt) · [Payment reminder email prompt](https://learn.ynteractive.com/content/prompts/payment-reminder-email-prompt) ## Frequently asked questions **How many dunning emails should I send?** Enough to cover each stage of your policy before a person steps in. The lesson's policy has three written stages and a hand-off after 60 days. **Can I mention late fees in a reminder?** Only if your agreement with the customer includes them. The lesson's GPT is told to mention a late fee only when the client's engagement letter has one. Rules on fees vary, so check with a professional if unsure. [All AI glossary terms, A to Z](https://learn.ynteractive.com/content/glossary) · [Free prompt templates](https://learn.ynteractive.com/content/prompts)