1. Open Automation Settings and review Invoice Generation and any advanced billing-cycle or domain settings.
2. Confirm that the system cron completes its daily tasks. A working client area does not prove that recurring invoices are being generated.
3. Inspect a representative service's Next Due Date, billing cycle, status and renewal settings.
4. Review Continuous Invoice Generation in General Settings if the business intends to issue later-period invoices while earlier invoices remain unpaid.
5. Check the next automation report and compare the generated invoice period with the intended service schedule.

Search existing invoices and line items for the same service and period, including cancelled documents. WHMCS tracks invoice generation separately to prevent producing the same service period repeatedly. Deleting or cancelling an invoice does not necessarily make the next cron recreate it.

Check whether the service is in an eligible state, whether renewal is disabled and whether its date falls within the lead-time window. With continuous generation enabled, Next Invoice Date and Next Due Date represent different parts of the billing process. Record both when escalating a date issue.

For a separate manual charge, create a draft invoice from the client profile or New Invoice action, add the agreed description and amount, review tax and dates, then publish it. A custom one-time invoice does not automatically become a recurring service charge.

Before correcting an existing published invoice in WHMCS 9.0, use the documented reissue or adjustment process. Review related service dates and payments so that the correction does not create another renewal action for an already paid period. Keep the reason linked to both the original and replacement records.

• Change a WHMCS service due date without creating a billing gap
• Diagnose a WHMCS cron that runs without completing automation
• Correct a WHMCS invoice without losing its audit trail
• Configure recurring and one-time WHMCS product prices

• WHMCS billing logic
• WHMCS automation settings
• WHMCS 9.0 invoice management
• WHMCS: reissue an invoice