The general rule for employees’ expenses: wholly and exclusively: example
A professional footballer is advised by his employer to increase his calorific intake.He requires an intake of 4,500 calories each day to provide enough fuel to get throughtraining and competitive matches. His current intake is only 3,500 calories each day. Adietician advises him about the sort of food he should be eating to make up thedifference. He asks for a deduction for the cost of the extra food. While he accepts thathe cannot deduct his normal food intake he argues that the extra food is not to keep himalive but is wholly and exclusively eaten to provide fuel to carry out the duties of hisemployment.
No deduction is due. It is not possible to distinguish between that part of his foodintake that gives him energy to do his job and that part that merely keeps him alive.Different jobs require different calorific intake and it is not possible to deduct anypart of it.
Example EIM31617 deals with an expense that can be apportioned.