Say I am a U.S. Citizen and travel to another country, and while there I buy food at some restaurant or whatever that's no longer tangible; or maybe I buy something but only use it there and do not have anything on me upon return. Do I have to declare that? Or is "declaring" only for tangible items you're carrying with you? I just want to be on the safe side since I don't want to be fined or anything.
When you fly back to the US, you'll be given a Customs declaration form on the plane to fill out. It looks like this.
Question 15 is what you're interested in:
The total value of all goods, including commercial merchandise I/we have purchased or acquired abroad, (including gifts for someone else, but not items mailed to the U.S.) and am/are bringing to the U.S. is:
In other words, add up the value of everything you are bringing into the US that you didn't have before and write it in the box. If you aren't bringing it back with you into the country, don't include it. If you already owned it before you left the country (e.g. your clothes, cell phone, etc...), don't include it.
Meals already in your stomach have a value of $0.
You have to declare anything you bought abroad and bring back to the US (beyond your allowances).
You do not need to declare any goods you consumed, threw away, or gave away while abroad.