If you use the credit limit function within QuickBooks, All Orders can provide information on a customer's credit status at order time. To enable, CHECK 'Check credit limit before saving sales order' in Sales Order Preferences.
Create an order in the normal fashion, now when you click Save you will get a dialog that looks like the following.
All Orders will deduct the accounts receivable (A/R) balance from the credit limit as well as deduct:
Open Orders: sales orders that have not been shipped
This order: the current sales order that you are saving
Open Ship Docs: Ship docs that have not yet been invoiced in QuickBooks.
Please note for users of QuickBooks version 2007 or earlier (Enterprise 7 or earlier), the A/R balance may not get updated during a sync as these version did not allow date filtering on A/R balances.