It really doesn't matter if it's spent in the US or abroad. At the time it is spent, you need to take the difference in transaction rates. It's the same concept

It really doesn't matter if it's spent in the US or abroad. At the time it is spent, you need to take the difference in transaction rates. It's the same concept as if you are making payments in something like Bitcoin. Unfortunately I don't have any sources on hand, but I have a friend that forex trades and I myself have been following the cryptocurrency regulation scene and the same rules transfer to here. However, this is one of those things where the government isn't going to come knocking your door down for since it's petty cash.