EDC § 22313

(a) No adjustment shall be included in new rates of contribution adopted by the board on the basis of an investigation, valuation, and determination or because of amendment to the Teachers’ Retirement Law with respect to the Defined Benefit Program, for time prior to the effective date of the adoption or amendment, as the case may be.

(b) No action of the board, other than correction of errors in calculating the allowance or annuity at the time of retirement, disability or death of a member shall change the allowance or annuity payable to a retired member or beneficiary prior to the date the action is taken.