(1) Except as provided in (2) , the formula for determining contributions due under Option 1, 19-20-716, MCA shall be a percentage of the termination pay, based upon the member's age at the time of retirement, times the total years of creditable service.

(2) Upon disability retirement, the contributions due to

adequately compensate the system for the additional benefit for termination pay under Option 1, shall be based on 15 years or the member's total years of creditable service, whichever is greater.