EIM32410 - Other expenses: assistant's wages
As a general rule, payments made by an employee to someone else for assistance in carrying out the employee’s duties will not be deductible under Section 336 ITEPA 2003.
If another holder of that job could carry out all of the duties without assistance the expense could not be one that each and every holder of the employment would have to incur, see EIM31640. Also, the expense is not incurred in performing the duties of the employment but in paying someone else to perform those duties, see EIM31650.
This rule was approved by the Courts in the cases of Lothian v Macrae (2TC65) and Jardine v Gillespie (5TC263).
There are a number of exceptions to the general rule, see EIM32415.