The main reason of having this proof is to make sure that if you enter Switzerland, you have a place to stay, and won’t roam during the night. And that if something happens, immigration is able to track you.
So it does not matter whether you choose the prepaid or the flexible rate, as long as you put the details of the hotel and are able to show a reservation confirmation.
You don’t have to prepay. (In fact, in most hotels, you pay when you check out, not when you make a reservation; often you cannot prepay.)
Credit:stackoverflow.com‘