SE31826 - Travel expenses: general - choice of route - example

During the course of a business trip an employee takes the opportunity to visit his mother. If the cost of his journey would otherwise be deductible, the fact that he makes a social call on the way does not affect that. However, if the social call involves a significant detour, that detour is not in the performance of the duties of his employment and is not attributable to attendance at a particular workplace (where the journey is in 1998/99 or a later year). So the cost of the detour is not deductible.