(a) The full amounts of COLA's are payable on annuities having a commencing date more than 11 months before the effective date.

(b)

(1) Prorated portions of COLA's are payable of annuities having a commencing date within 11 months before the effective date.

(2) Proration is based on the number of months (with any portion of a month counting as a month) between the annuity commencing date and the effective date.

(3) For survivors of deceased retirees, proration is determined by the date the annuity was first payable to the deceased retiree.

(4) Proration applied to the assume social security disability insurance benefit is based on the commencing date of the disability annuity, not the beginning of the social security disability benefit.