The right to any pension, annuity, allowance, or benefit; the right to the return of contributions; a pension, annuity, allowance, or benefit itself; any optional benefit; any other right accrued or accruing to any person under this chapter; and any moneys under this chapter shall be exempt from any tax imposed by this state or any county, municipality, or other political subdivision, except as provided in Code Section 48-7-27.