The Bureau of Labor Statistics has scheduled the September 2026 Consumer Price Index for release at 8:30 a.m. Eastern time on October 14, the last monthly reading needed to calculate the cost-of-living adjustment that will apply to Social Security and Supplemental Security Income checks in January 2027. Until that release, the 2027 adjustment is not a published number, and the 2.8 percent figure on Social Security’s website belongs to the previous cycle rather than serving as a forecast of the next one.
The distinction matters because inflation readings are already public and are easy to mistake for the answer. The wage-earner index rose 3.5 percent over the twelve months ending in August 2026, but that is a single month compared with the same month a year earlier, not the quarterly comparison Social Security uses. The final input to the adjustment still waits on a calendar date.
The 2.8 percent on Social Security’s page is the 2026 adjustment
Social Security’s cost-of-living adjustment page states that the latest COLA is 2.8 percent for Social Security benefits and SSI payments. That adjustment took effect for December 2025 and reached checks in January 2026. The page shows its arithmetic: a third-quarter 2024 average of 308.729 and a third-quarter 2025 average of 317.265, which gives (317.265 – 308.729) / 308.729 x 100 = 2.8 percent.
The agency’s year-by-year COLA table carried no 2027 entry when it was read on October 2, 2026. A chart, social post or phone answer that attaches 2.8 percent to 2027 is carrying last year’s number forward under a new date.
The September index completes a July-to-September average
Social Security’s published formula defines the adjustment as the percentage increase in the Consumer Price Index for Urban Wage Earners and Clerical Workers (CPI-W) from the third-quarter average of the prior year to the third-quarter average of the current year. For the 2027 adjustment, the starting line is the 2025 third-quarter average of 317.265. The comparison quarter is July, August and September of 2026.
August is the latest month on the books. The Bureau of Labor Statistics release of September 11 put the CPI-W at 328.481 (1982-84=100), up 3.5 percent from a year earlier. That reading is one of the three months inside the quarter. It is not the quarterly average, and a twelve-month change in one month does not stand in for the comparison Social Security makes. The September index is the third month, and the percentage cannot be called official before it is out.
Why the October 14 time slot leaves no earlier source
The BLS release schedule lists the September 2026 reference month for Oct. 14, 2026, at 08:30 AM. The row ahead of it is the August reading, released Sept. 11, and the row after it is the October reading, due Nov. 10. Nothing on the schedule offers an earlier official look at the September index, so any January-check figure circulated before 8:30 a.m. on October 14 is an estimate by whoever published it.
The same limit applies to a household’s own arithmetic. The percentage comes from two quarterly averages, and only one of them is complete. An estimate built from August alone can land on either side of the final figure, because the September reading moves the three-month average.
The Part B premium is announced on a separate calendar
The COLA percentage is only the first of two numbers that decide a January deposit. For beneficiaries whose Medicare Part B premium is withheld from their Social Security payment, the check is the benefit after the adjustment, less the premium. The premium has its own announcement, and no 2027 premium had been published as of October 2, 2026.
That leaves a gap between the day the percentage is known and the day the net change in a check can be worked out. On October 14 the gross increase can be calculated for any benefit amount. The deposit that results for a beneficiary with Part B deducted cannot, until the premium is published. SSI payments follow the same adjustment, according to the Social Security page, and the premium question applies to SSI recipients only where a Medicare premium is involved.
The most recent official premium schedule is the Centers for Medicare & Medicaid Services fact sheet for 2026, published November 14, 2025. It set the standard monthly Part B premium at $202.90 for 2026, an increase of $17.90 from $185.00 in 2025, with an annual deductible of $283. Those are 2026 figures, and the agency’s page carries no 2027 numbers.
Reading a January deposit against two unpublished numbers
The 2027 cost-of-living adjustment has no figure until the September 2026 index is out, and the Medicare Part B premium that comes out of the same check has no 2027 figure at all. Matching a deposit to what a notice says is left to each recipient, and a payment that arrives short or late starts with the same notices and dates.
The Social Security Check Protection Kit includes the 2026 payment calendar, a first-24-hours plan for a late or missing payment and the three SSA forms that stop or pause collection, arranged for checking a deposit against a notice.
See the payment calendar and late-payment plan in The Social Security Check Protection Kit →
This article was drafted with AI assistance from the cited official sources and checked against them before publication.
David M. Keller is a finance writer based in Columbus, Ohio, covering personal finance and consumer-focused economic topics. He earned his degree in journalism from Ohio University and began his career reporting on local business and economic trends for a regional media outlet. Since then, he has contributed to a variety of online publications, focusing on clear, practical coverage of topics such as cost of living, debt, and everyday financial decision-making.
