1. How much tax does the mayer pay?

2. How much cost does the mayer pay?

(Which one is correct?)

4 answers

The first is correct. Note the correct spelling is mayor.
1. How much tax does the mayor pay?
2. How much cost does the mayor pay?

(Thank you for your help......If we use the verb 'cost,' what do we have to do to make Sentence 2 correct?)
3. How much does it cost for the mayor to pay tax?

(Is this grammatical?)
Yes, 1 and 3 are correct.

3 would be better if you said, "mayor to pay taxes" or "mayor to pay the tax."