Answer: 30.3%
Step-by-step explanation:
Because taxes are not paid on municipal bond interest, their interest rates are usually lower with the difference accounting for the taxes paid.
For a municipal bond to be similar to a corporate bond, the tax rate must be such that it makes them equal:
Municipal bond return = Corporate bond return * (1 - tax rate)
5.75% = 8.25% * (1 - tax)
1 - tax rate = 5.75% / 8.25%
1 = 0.6969697 + Tax rate
Tax rate = 1 - 0.6969697
= 30.3%