In the case of training awards, certain appointment paperwork for the trainee is often required before the trainee can be paid (such as an appointment via xTrain for trainees on an NIH award).  Because this paperwork often cannot be submitted until an initial award or continuation funding has been received, this would prevent the billing agreement from being established.  However, each case would be handled based upon the terms of the particular training award and the risks of the situation at hand.