What are the two types of taxes or duties mentioned in Article 274 that require prior recommendation of the President?
The two types of taxes or duties mentioned in Article 274 that require prior recommendation of the President are:

1. A tax or duty, the whole or part of the net proceeds whereof are assigned to any State; and
2. A tax or duty by reference to the net proceeds whereof sums are for the time being payable out of the Consolidated Fund of India to any State.