Originally Posted by Roger

That's frowned upon by HMRC in the UK who persist with the 'wholly, necessarily and exclusively' rules. This doesn't apply to MPs, though.

Per diems can work well as they simplify expenses calculations immensely. I remember organising events in Germany and elsewhere for a previous multinational employer with staff participants from a dozen or more countries. Most were happy with their per diems, the Brits had to save all their receipts and claim after the event.