1. Open the product's Pricing tab and confirm its recurring cycles and complete period prices.
2. Enable Prorata Billing and enter the intended Prorata Date.
3. Set Charge Next Month according to whether orders near the end of a period should also pay the following period.
4. Review addon prorata settings and available cycles. Matching a billing day does not mean a monthly service and annual addon become the same term.
5. Save and test orders before and after the chosen cutoff, including a late-month order and a February date.

Write the actual service period on the first invoice and in the order explanation. A customer ordering late in a month may pay for the remaining days plus a full following period, depending on configuration. That larger first amount should be explained as a covered period rather than described as an extra setup charge.

WHMCS uses special values for Charge Next Month: zero always includes the next applicable cycle, while 32 disables that behavior. Test the saved result instead of assuming that zero means disabled.

Assume a monthly product has Prorata Billing enabled, Prorata Date = 1 and Charge Next Month = 20. These illustrative dates show the periods to check in a test order.

The later order crosses the configured cutoff, so its first payment covers the remaining days of October and November. Describe those dates on the order and invoice instead of calling the larger amount a setup fee.

Confirm the actual calculated amount and next due date in your installation. This monthly example does not define how a quarterly or annual addon should be charged; test each advertised cycle separately.

For addons, the parent product supplies the relevant prorata date, and the available billing cycles affect the resulting schedule. Test an addon bought together with the product and one bought later. Verify both its first invoice and its next due date.

Changing a product's prorata setting applies to new orders. Existing services require an intentional date and billing review. Before aligning an existing customer's dates, identify already generated invoices and paid periods so that the customer neither loses paid time nor receives overlapping charges.

Keep the approved schedule in the product's internal documentation and review it after pricing or addon changes.

• Configure recurring and one-time WHMCS product prices
• Change a WHMCS service due date without creating a billing gap
• Create recurring service addons in WHMCS
• Control when WHMCS generates recurring invoices

• WHMCS prorata billing
• WHMCS products
• WHMCS product addons