R.I. Gen. Laws § 45-21-45: Tax exemption.

The right of a member or beneficiary to a pension, an annuity, a retirement allowance, to the return of contributions, any benefit or right accrued or accruing to any person under the provisions of this chapter, and the moneys of the retirement system created under this chapter, are exempt from any municipal tax or state tax except for the personal income tax imposed under the provisions of chapter 30 of title 44.