The Subaccount drop-down menu allows you to choose a specific or all subaccount number (s) to query CCBill's system for information. In some areas, you will only be able to select an individual subaccount. Typically, you will be presented with the following:
The subaccount is used as part of the main account. For example, if 900000-0000 is used as the main account, then 900000-0001 is a valid subaccount for the main account. Most reports allow you to choose all subaccounts or a specific subaccount.
Keep in mind that the subaccount number is associated with certain website information. Many accounts have several subaccounts, which are actually individually processing website accounts.