Fiserv evaluates payment direction based on a proprietary algorithm that takes into account many factors.  Some evaluation is done at the sponsor level, some at the merchant level, and some at the subscriber level.  Sponsor level information determines what check types are acceptable – draft only or draft and corporate.  Merchant level information determines the preferred payment method for that payee (electronic or paper) and if the merchant assumes responsibility for returns.  Subscriber level information such as claims and payment history also factor into the decision.  

Each payment request is evaluated individually and may change each time a payment processes.  That’s why, in some cases, payments made by the same subscriber to the same merchant may result in different payment methods.  The only true difference between these remittance methods is the timing of the debit.  For corporate checks, the debit occurs on the date the payment is due, regardless of when the payment posts at the merchant.  For draft payments, the debit occurs on the date the merchant posts the funds to the subscriber’s account.  Regardless of the payment method, funds will not be withdrawn from your account prior to the due date the subscriber schedules.