Abstract: A method, using a computer system, for underwriting the risk of non-payment associated with processing non-cash payments on behalf of a merchant by managing balances in pledged collateral accounts owned by one or a plurality of underwriters. The invention determines the initial amount of required collateral, in total and for each participating underwriter, as a function of estimated sales and recalculates required collateral, as payment transactions and other transactions affecting collateral accounts occur. In the event of an anticipated underwriter collateral shortfall, the underwriter is notified that a collateral increase is required. Payment processing is suspended if collateral shortfall is imminent.