That's what they do with deposit@home. I don't think USAA cashes the checks immediately when you cash your checks online. That's why they require you to have a line of credit with them. When you cash a check they give you an interest free loan for the amount of the check. When the check clears the loan is paid off. And if the check doesn't clear they have the ability to take the money out of the account, or they actually give you a loan to cover the check if you have drained your acccounts.