What documentation do I need to substantiate entertainment expenses?

Costs incurred while entertaining customers, prospective customers, clients, suppliers, employees and other business associates are valid business expenses that are subject to conditions and restrictions. For entertainment costs to be deductible, the following must be documented: the time, place and nature of the entertainment, a description of the business purpose involved, the amount of each separate expense, the business relationship and identification of the persons entertained. A calender diary is recommended to maintain this information.