I can't find the FAA opinion but this article refers to it.
Pilot Counsel
As has been pointed out above, there is no fuel regulation after you have taken off. You use as one example a long taxi, that could be a violation as you took off without enough fuel. So if you land with 35 minutes fuel, as long as you can show you departed with enough fuel, it is not a violation.
And in the US if you require an alternate airport, no matter what the weather at your destination, the alternate must be a different airport.