If you accept that a particular overseas trip has been made
necessarily to carry 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
EIM31660. 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
EIM31811.
