What if we plan for 50 attendees and the venue charges for 50, but only 45 show up, putting the meal cost per attendee over the per diem?

First, in planning the event and selecting the meal to be served, every effort should be made to have a margin between the planned meal cost and the allowable per diem. This will allow some cushion for no-shows before the per diem is exceeded. However, if the per diem is exceeded and the amount is reasonable, under the circumstances we would consider the additional cost allowable. There is still a possibility that an auditor would disagree and deem the excess unallowable.