This hasn’t been much of a secret through the travelling world, but as you know taxes is a killer, most hotel chains that allows booking on points or cash + points do not levy taxes on the booking which in turn is another heap of savings.
Some specific hotels might charge taxes though, it’s best to email the hotel or do a dummy booking (with no cancellation penalty) and make sure so there’s no hidden surprises on check-out.
When booking cash option some counties hotel rates are still subject to taxes AND service charges to the tune of 10%, 14%, 14.75% in USA, UAE its 20%, Maldives 18.8%, Turkey 8% and in Oman its 17%, now remember that Oman currency is ZAR R29 to 1 Omani riyal! if you do the math it adds thousands to a stay.
Remember this when booking in room dining and other hotel services as most times prices quoted are subject to taxes. ( It doesn’t end there… there is still tourism fees and bed taxes some might add, ( Dubai recently implemented a tourism fee of AED10-20 per room per night charge ( to help fund their 2020 Expo), New York adds a city tax of $3.50 whilst Maldives adds USD $8 per person bed tax per night).
I’ve used points bookings (free nights) at all the above places and more and non of all the crap above was charged to my accounts upon check-out. This probably wont last forever as hotel policies are ever changing.
Here’s a Dubai sample:
Here’s a Maldive sample:
Billing proof :
Points posting to my account:

Points posted correctly at 10 points per USD spent. Bonus points added as per IHG Elite Platinum member.