All customers should be validated periodically to check for errors in their accounts. A good time to do this is just before each billing cycle. To do so:
1. Go to Utilities: Administration: Billing: Customers: Configure.
2. Click Validate all Customers.
3. A report will be generated showing any customer accounts that have errors (e.g., customer has no lists assigned; or no expiration date for credit card).
4. Click Editto change the customer information.
More
1. Billing
3. Adding, Validating and Syncing Servers
5. Creating Additional Charges
8. Assigning Hosting Plans, Charges and Lists
9. Validating Customers
10. Running Bills
15. Billing Reports
17. Viewing a Customer's History