Taking a monthly payment is easy. Handling everything that happens around it is where subscription products lose revenue and customer trust. Plan for these cases before launch, not after the first angry support ticket.
Failed payments
Cards expire, get cancelled or hit their limits. A share of your renewals will fail every month. Use your payment provider's smart retries, email customers before and after a failed charge, and give them a grace period with a clear banner in the app before you restrict access.
Upgrades, downgrades and proration
- Upgrades usually apply straight away, with a prorated charge for the rest of the period.
- Downgrades usually apply at the next renewal, so customers keep what they paid for.
- Decide what happens to data or seats above the new plan's limits.
- Show the customer exactly what they'll pay before they confirm.
Taxes
Depending on where your customers are, you may need to charge sales tax or VAT and show it on invoices. Rules vary by country and region, so use a billing tool that calculates tax for you, and check your obligations with an accountant.
Webhooks are your source of truth
Don't grant access just because the checkout page said "success". Listen for your provider's webhooks, verify their signatures, and handle them idempotently. They can arrive twice, or out of order.
Test the unhappy paths
Use your provider's test cards and test clocks to simulate declines, renewals and plan changes months ahead. The edge cases you test now are the support tickets you won't get later.
