Social Security COLA 2027: The Formula and the 317.265 Base
As of September 2026, nobody knows the 2027 Social Security COLA — including the Social Security Administration. That is not a hedge. The law ties the number to a three-month average, and one of those three months has not been published yet. What you can know today is everything else: the exact formula, the base figure the 2027 adjustment will be measured against, and how much of the 2026 data is already on the books. This article walks through the SSA's own calculation, with the real CPI-W numbers it used for 2026, so you can do the arithmetic yourself the moment the last data point lands. It does not give you a forecast, and there is a section below explaining why the forecasts you have seen keep moving. Contents The formula, in the law's own words The 2026 COLA, worked out with real numbers What that makes the 2027 base: 317.265 The 2026 CPI-W data published so far Two rules that break naive estimates The month BLS never published ...