Originally Posted by Frequentlander

Some companies demand paper receipts for every single item. No receipt = no reimbursement. Some (most) accept scans but some actually want the physical original.
For self-employed people who travel for a number of client companies, conforming to each of their individual idiosyncrasies and how they want the taxes stripped out or not and reported or not is a nightmare.

As for currencies, I once did some work for a company in Little Rock, Arkansas and had to talk them through my expense claim because (and no hyperbole here) the person processing the claim had no idea that there was anything other than a USD and could not get their head around there being "other" currencies. That claim had USD, CAD and MXP so you might imagine how long it took me to get my expenses back.