You can configure when and how WHMCS invoices your customers.
Configure Invoice Settings
To configure how and when WHMCS invoices your customers:
1. Go to Configuration > System Settings > Automation Settings.
2. Locate the Scheduling section.
3. For Time of Day, select the time at which you want WHMCS to run invoicing and other automated tasks. By default, WHMCS runs invoicing and other automated tasks at 9AM local server time.
By default, WHMCS runs invoicing and other automated tasks at 9AM local server time.
4. Locate the Billing Settings section.
5. For Invoice Generation, enter the number of days before the Next Due Date to generate invoices.
By default, WHMCS will generate invoices 14 days prior to the Next Due Date.
Click Advanced Settings to specify different numbers of days in advance to generate invoices for different billing cycles. For example, the system could generate invoices for monthly billing cycles nine days in advance and for annual billing cycles 30 days in advance.
6. To send invoice payment reminder emails after the initial invoice generation email, check Payment Reminder Emails.
7. If you checked Payment Reminder Emails, enter the number of days before the invoice due date to send each reminder email. Enter 0 to disable an email.
Enter 0 to disable an email.