SE31965 - Travel expenses: general - overseas conferences, seminars and study tours - apportionment

If you accept that a particular overseas trip has been made necessarily in carrying out the duties of the employment you may still find that some expenses are not deductible. For example, a short break may be taken during an overseas conference.

You should not accept an apportionment of the total cost of the trip on a percentage basis, calculated by looking at the relative time spent on business and non-business activities. There is no basis in law for such an apportionment, see SE31660. Instead you should examine the expenses individually and permit a deduction only for those that are necessarily incurred.

The correct approach is illustrated by example SE31811.