For years I've traveled LAX-JFK, departing Thursday afternoon or evening, arriving home Friday morning. In expense reports, I've submitted full-day per diems Thurs, and breakfast per diems Fri. Always approved without issues. Recently the company reworded their expense guidelines and I found it ambiguous. When I asked a boss what I do in this scenario, the reply was I should submit 75% of the full per diem on Thurs, and nothing on Fri. Also "We don't make the rules, we follow gsa.gov." (I don't work in government, if relevant).

I can't submit taxi or uber tips as an expense, since that's considered part of the per diem, so it seems odd being told I also can't submit a per diem on Friday given I always have a taxi or uber then.

So I reviewed gsa.gov and see it says that on travel days, per diem for "last day of travel" is 75%. But it doesn't define -- which day is the"last day of travel" when you arrive home the day after you depart? I.e in my case, is my last day of travel considered Thurs or Fri?