In WHMCS, invoice generation is the process of creating invoices for services or products that have been ordered by clients. You can configure WHMCS to automatically generate invoices based on your settings. Here's a step-by-step guide on how to handle invoice generation in WHMCS:

1. Login to WHMCS:

   • Access your WHMCS administrator dashboard using your credentials.

2. Navigate to Invoice Settings:

   • From the main menu, go to "Setup" > "General Settings".

3. Configure Invoice Settings:

   • Scroll down to the "Invoice Settings" section.

   • Here, you'll find various settings related to invoice generation:

     • Auto Redirect on Checkout: Decide whether clients are automatically redirected to the invoice upon checkout.

     • Auto Redirect on Checkout with Product: Set if clients should be directed to the invoice if they only order free products/services.

     • Create Invoice on Order: Choose whether an invoice is automatically generated upon order placement.

     • One-Time Invoice Generation: Indicate if one-time invoices are automatically created for services/products.

     • Prorata Due Days: Specify the number of days before the due date for prorata invoices.

     • Prorata Overdue Days: Set the number of days before prorata invoices become overdue.

     • Send Reminder for Unpaid Invoices: Decide if reminder emails are sent for unpaid invoices.

     • Send Invoice Overdue Notices: Determine if overdue notices are sent for unpaid invoices.

     • Invoice Generation Method: Choose between "Standard" (invoices generated immediately) and "Separate" (invoices generated for each item on the order).

4. Save Changes:

   • After making any necessary adjustments, click "Save Changes" to apply the invoice generation settings.

5. Testing:

   • Place a test order through the WHMCS client area to ensure that invoices are generated correctly based on your settings.

6. Viewing and Managing Invoices:

   • To view and manage invoices, go to "Billing" > "Invoices" in the WHMCS admin area. Here, you can search, view, and take action on invoices.

7. Send Manual Invoices (Optional):

   • If needed, you can manually generate an invoice for a specific client by going to "Billing" > "Create Invoice" in the admin area.

8. Regular Review:

   • Periodically review your invoice generation settings to ensure they align with your business requirements.

Remember to refer to WHMCS documentation and support resources for detailed information on each of the invoice generation settings. Additionally, always keep backups of your data and configurations to prevent any potential data loss during the setup process.