After retirement, the tier I portions of both employee and spouse annuities are generally increased for higher living costs at the same time, and by the same percentage, as social security benefits. These increases, effective December 1 and included in the January payment, are based on the rise in the Consumer Price Index from the third quarter of the last year a cost-of-living adjustment became effective to the corresponding period of the current year. Generally, if the Index increases by 5 percent, for example, the tier I portion increases by 5 percent.