(a) All retirement annuity payments, other benefit payments, and a member's accumulated contributions are unassignable and are exempt from execution, garnishment, attachment, and state and local taxation.
(b) Notwithstanding Subsection (a), the board of trustees by rule may authorize the retirement system, in accordance with a retiree's voluntary election, to:
(1) deduct qualified health insurance premiums from the retirement annuity otherwise distributable to a retiree who is an eligible public safety officer or a retiree who meets any expanded eligibility provision for a similar tax exemption under subsequent federal legislation; and
(2) pay the deducted amount directly to the health plan provider, subject to the requirements of Section 402(l), Internal Revenue Code of 1986, or other applicable federal law, and the rules adopted by the board.