A lending institution computer establishes a line of credit coupled to a prepaid card account and makes available draws to the line of credit line in an authorization stream for a proposed purchase using the prepaid card account as payment. When the line of credit is accessed, the prepaid card account is loaded with an additional value of one or more predetermined loan increments so that the prepaid card account then has a new amount totaling a previous amount plus the amount of value of the one or more preselected loan increments and so that the new amount exceeds or equals the value of a proposed purchase. Next, a new value for a line of credit balance available is determined, accounting for value loaded onto the prepaid card account and a predetermined loan advance fee for each loan increment loaded onto the prepaid card account.