Most pay day loans are a loan which has a post dated check as collateral. The customer can pay off the loan before deposit day or allow the check to be deposited. If the check is good when deposited, all is well and good and the birds will continue to sing. If not, the lender is left to collect the bad check. There is much discussion as to the validity of a post dated check and to what extent collection can be persued since the lender knew that it was NSF when written.