How the 2027 Social Security COLA Gets Decided — and What July's Inflation Data Adds

Every autumn the Social Security Administration announces a cost-of-living adjustment, and every autumn the number arrives as if someone decided it. Nobody decides it. It falls out of a formula, and the formula is now roughly one-third resolved for 2027.

The formula

The COLA is based on the Consumer Price Index for Urban Wage Earners and Clerical Workers — CPI-W — which the Bureau of Labor Statistics publishes monthly. The calculation compares the average CPI-W for the third quarter of the current year against the average for the third quarter of the last year in which a COLA was determined. Third quarter means July, August and September. If the current year's average is higher, the percentage increase becomes the COLA, rounded to the nearest tenth of a percent. If it is not higher, there is no adjustment.

Two details are worth holding onto. First, the index is CPI-W, not the more widely quoted CPI-U. CPI-W is built from the spending patterns of urban wage earners and clerical workers, a narrower population than the all-urban-consumer basket. Second, only three months matter. Inflation in January or in December is irrelevant to the arithmetic except insofar as it shows up in those three summer readings.

What the July reading tells us

BLS published the July 2026 CPI report on August 12, 2026. It put the CPI-W index at 327.104, on the 1982-84 = 100 base, up 3.4% over the previous 12 months. The all-urban CPI-U rose 0.1% on the month, seasonally adjusted, and was also up 3.4% over 12 months unadjusted, with the index at 333.918. Core CPI, excluding food and energy, was up 2.5% over 12 months.

• Shelter rose 0.1% on the month and accounted for roughly two-thirds of the monthly all-items increase.
• Energy fell 1.5% on the month.
• Gasoline fell 2.9% on the month.
• Food rose 0.1% on the month.

That is one of three months. August and September CPI-W readings are still to come, and both carry equal weight in the average.

For context, the recent record

• January 2022: 5.9%
• January 2023: 8.7%
• January 2024: 3.2%
• January 2025: 2.5%
• January 2026: 2.8%

The 2026 adjustment of 2.8% was announced on October 24, 2025. The agency notes that announcing in October gives beneficiaries time to plan before the change takes effect with January benefits.

Why the formula gets argued about

Because CPI-W reflects the spending of working-age wage earners, critics have long argued it understates the cost pressures facing retirees, who spend a larger share of income on health care and housing and less on transportation to work. An alternative index, CPI-E, tracks a population aged 62 and over and has at times run higher. Switching indexes would require Congress to act; the statute currently points at CPI-W.

The mechanism itself was a reform. Congress enacted the automatic COLA provision as part of the 1972 Social Security Amendments, and the adjustments began in 1975. Before that, raising benefits required passing a bill, which meant increases were irregular and politically contingent. The formula traded discretion for predictability. The trade-off is that in a year when the index moves in ways that do not match a household's actual bills, there is no one to appeal to.