I'm an offshore contractor working for a US company. I recently went to visit them. They paid for flights and hotels. In addition, I billed all my expenses while I was there (Uber rides, food, visa application fee, trains in my home country, US SIM card, travel insurance, etc.). My contract doesn't say anything about what I can expense in this event, nor did we really agree on anything in advance.
My employer isn't happy with this and says thry doen't want to pay for anything that wasn't specifically agreed upon in advance. My opinion is that everything required for me to undertake a business trip at their request is billable. Personal stuff of course isn't.
What is normally considered appropriate to bill when going on a business trip?