Going to a show

My client regularly sends employees to trade shows in Europe and beyond. Naturally the employees need a passport and occasionally visas to attend these shows.

The employer pays for the costs of visas and passport renewals and the initial passport applications if a new employee does not already have a passport.

My client of course argues that these costs are for business purposes; am I right in claiming them as a tax deduction?

Secondly should they be declared as a benefit in kind? My thought is that if a person already has a passport then associated expenses would not be ‘wholly exclusively and necessarily’ incurred in performing the duties of the employment.

But what if the employee had never been abroad on holiday and only applied for the passport because it was needed for business trips abroad?

Would all of the expenses then be allowable and what...