Are the following sentences acceptable?
a) How much is your rent?
b) How high is your rent?
That's interesting. So a bank adviser taking a customer's details would definitely not use b)? Is "What is your rent?" more appropriate than a) or the same?
In a general enquiry about financial expediture "How much is your rent?" or "How much rent do you pay?" would seem the most likely to me.
That's right. It would be if the bank representative was a loan officer or financial adviser.
"How much do you pay?" or "What is your rent?" are also possibilities. (As far as I can tell, nobody is in disagreement with anybody.)
"The second comes from a person who thinks that rents in general or yours in specific is too high." That's what MikeNewYork said about "How high is your rent?"