Sign in to the client area and open Billing > My Invoices, or select Invoices from the dashboard. Open the invoice you want to pay, confirm the amount and due date, choose an available payment method, and follow the checkout instructions.
After a successful payment, allow a short time for the payment gateway and WHMCS to update the invoice. If money was deducted but the invoice remains unpaid, do not pay twice; open a billing ticket and include the invoice number and payment reference.
