Electronic checks are currently handled by the U.S. banking system as Automatic Clearinghouse transactions, and are used by organizations such as Checkfree(tm) and by insurance companies to automatically take money out of your account each month for premiums, etc If you use the ACH system, you can't pre-authorize sporadic payments for arbitrary amounts. Since the receiving institution enters the transaction into the ACH, and since the security environment of the ACH is, er, primitive to what can be accomplished with public key techniques, each transaction amount must be specifically authorized with a piece of paper. Individual transactions can be authorized, as well as periodic payments such as loans and insurance premiums. With Checkfree, the sender must separately authorize each payment, as I understand it. The receiving institution cannot ask for payment. It's a hole in the payments system--an electronic way for individuals to give authorization to take money from their accounts on a per transaction basis. Eric