For purposes of computing optional forms of benefit provided in the Retirement Act, the interest used shall be 8.50% per annum and the mortality rate shall be 52% of the rate in Table A, column A plus 48% of the rate in Table A, column B for members and 48% of the rate in Table A, column A plus 52% of the rate in Table A, column B for surviving beneficiaries of members.

(Source: Amended at 23 Ill. Reg. 3824, effective March 9, 1999)