The word "dunning" sounds archaic - it comes from a 17th-century term for politely insisting on payment. The mechanics are very modern. Every recurring billing system has some percentage of charges fail every month (typically 5–10%). Without intervention, those failures convert directly to churn - and to lost revenue from customers who actually wanted to keep paying. Dunning is the system that gets those payments through.
Why payments fail (involuntary churn)
- Expired card. The customer's card expired and the new one has different digits or a new expiration date.
- Insufficient funds. Particularly common on debit cards or near the end of the month.
- Card limit hit. Credit limit reached just before the recurring charge tried to clear.
- Fraud flag. The customer's bank flagged the recurring transaction as suspicious and blocked it (more common after the customer travels or shops at an unusual merchant).
- Bank-side technical error. Random failures that resolve on a retry.
None of these are the customer's active decision to cancel. They are friction - and friction is recoverable.
What a good dunning system does
- Smart retries. Instead of retrying immediately, wait for patterns that match how issuing banks reset card limits and clear holds - typically 1, 3, 5, and 7 days after the initial failure. Some systems use machine learning to optimize the schedule per card-issuer.
- Card updater integration. Visa Account Updater and Mastercard Automatic Billing Updater push new card numbers to merchants when customers get reissued cards. A dunning system that uses these recovers many failures automatically without the customer ever knowing.
- Email cadence. "Your payment failed" → "We're trying again in 2 days" → "Last attempt - please update your card." The tone should be helpful, not threatening. The CTA is always: update your card.
- One-click recovery. The email link should land the customer on a pre-authenticated payment-update page, not a login screen. Every extra click is a recovery you don't get.
- Eventual pause or cancel. After all retries fail, the subscription pauses or cancels cleanly - and triggers a win-back sequence rather than disappearing silently.
How much revenue dunning recovers
For most Shopify subscription businesses, dunning recovers 30–50% of failed-payment churn. On a subscription store doing $100K/month with 8% monthly payment failure, that's $2,400–$4,000/month in saved revenue. Good dunning typically pays for itself within the first 30 days.