The government tax on most of the international branded hotels in India is stated as 12.5% of the rate at the time of booking. However, note that some hotels (namely Intercontinental Hotels Group) argues that it is 12.5% of some officially published room rate that is likely to be higher than your quoted rate on various websites. We're currently talking to the IC Grand in Delhi about this matter specifically.
Some hotels are advertising the taxes as "Tax@
Rack Rate of 12.50% per room per night is not included in the rate" and matters of the sort. This is true of Starwood (in the case quoted herein) and Intercontinental, etc.
Rack rate is not what most all of us are paying. This may push some people above the per diem amounts.
Edit: I did a bit more research into this:
The more "honest"/forthcoming hotel companies in this case are advertising the taxes as "Tax@Rack Rate of 12.50% per room per night is not included in the rate" and matters of the sort. This is true of Starwood (in the case quoted herein). Hyatt says: Additional Charges: 0.00% tax
12.50% occupancy tax". Intercontinental Hotels Group says: "Tax: 12.5% per night not included in rate effective 2 May, 2005 thru 3 May, 2005
GOVERNMENT LUXURY TAX". Marriott says: "*EXCL TX 12.5PCT ON RACK RATE*".
to the confusion.