The number that closed the books on Social Security’s 2027 raise is 330.654, the September level of the Consumer Price Index for Urban Wage Earners and Clerical Workers (CPI-W), which the Bureau of Labor Statistics released on October 14. It was the third and final monthly reading in the July-to-September stretch that sets the cost-of-living adjustment, and the Social Security Administration (SSA) announced the result the same day as 3.6 percent. Average the three months, compare them with the same quarter a year earlier, and the arithmetic comes to 3.619 percent before rounding.
For a retiree, the practical question is how a price index becomes a dollar raise and when the new amount shows up. SSA says the increase starts with benefits payable in January 2027 for Social Security, with increased SSI payments beginning December 31, 2026. Most beneficiaries can read the personal notice online in late November, and a mailed notice follows in December for those who do not use online accounts.
The index is settled, so the open item is the date the first deposit at the new rate arrives: December 31 for SSI recipients and January for Social Security. The Social Security Check Protection Kit includes the 2026 payment calendar for lining those deposit dates up.
Line up the 3.6% raise’s first deposit dates with the Social Security Check Protection Kit →
Three monthly readings, one quarterly average
FedSmith’s tally of the BLS series puts the CPI-W at 327.104 for July, 328.481 for August and 330.654 for September. Those three add up to 986.239, and dividing by three gives a third-quarter 2026 average of 328.746, against 317.265 for the third quarter of 2025. Each of those averages, not any single month, is what the formula compares. September’s reading matters because it was the last to arrive and the highest of the three.
The gap between the two averages is 11.481 points. Divided by the 2025 base of 317.265, that is an increase of 3.619 percent, which rounds to 3.6. SSA’s rule, as stated on its COLA page, is that the adjustment equals the percentage increase in the CPI-W from the third quarter of the last year a COLA was set to the third quarter of the current year. When the index shows no increase over that span, there is no adjustment.
September alone rose faster than the quarter did. BLS reports the CPI-W up 0.7 percent from August before seasonal adjustment and up 3.9 percent from September 2025. Had the raise been pegged to that single month, it would have been closer to 3.9 percent. Blending in July’s 327.104 and August’s 328.481 pulled the average, and so the raise, down to 3.619 percent.
What 3.619 percent does to a pension check
FedSmith worked the percentage through on sample benefits. A Social Security check of $2,100 a month rises about $76 to $2,176, by its figures. SSA’s announcement post states the overall average differently, saying the average retirement benefit rises by about $75 a month starting in January. The two numbers are consistent, since a rise on a larger or smaller check lands above or below the average.
Each tenth of a percentage point is worth about $2.10 a month on a $2,100 check, which is why the rounding step carries real money. A reading of 3.5 percent would have added about $73.50, while 3.7 percent would have added about $77.70. FedSmith also lists federal retirees: about $216 more a month on a $6,000 CSRS annuity and about $62 more on a $2,400 FERS annuity. The FERS figure works out to 2.6 percent, a smaller percentage than the Social Security raise.
The 328.746 baseline for next year
The CPI-W is one of two main consumer price indexes the bureau publishes. BLS’s September report shows the all-items index for all urban consumers up 3.7 percent over 12 months, against 3.9 percent for the wage-earner index behind the COLA. The core measure, which leaves out food and energy, rose 2.6 percent, so the headline rates carry a good deal of price movement from those two categories.
The third-quarter 2026 average now becomes the base for the next adjustment. Under SSA’s rule, the 2028 COLA will compare the July-to-September 2027 CPI-W readings with 328.746. If prices level off, the next raise could be much smaller than 3.6 percent, and if the index fell below that average there would be no raise at all.
From index to notice: what arrives when
The personal notice is the only place the exact new amount appears. SSA says the notices are posted in the Message Center of online accounts in late November for accounts created by November 18, and the agency mails notices in December to beneficiaries not enrolled in paperless delivery. Anyone without an account can start one at my Social Security.
A rough check is simple: multiply the current monthly benefit by 1.036. A notice that lands far from that figure, before any deductions, is a reason to call the agency and ask which numbers it used. Medicare beneficiaries see their new 2027 benefit amount in December, according to SSA, and the agency’s COLA page says that amount also appears in the mailed notice.
The 3.6 percent is the product of one rule applied to one quarter of prices. SSA’s COLA page notes that since 1982 the adjustment has taken effect with benefits payable for December, which beneficiaries receive in January, and that timing is why this index reading shows up in the first deposits of 2027.
After the index comes the deposit date
A 3.619 percent calculation turns into a raised check only on a specific date: December 31 for SSI recipients, with Social Security following in January. The 75-page Social Security Check Protection Kit includes the 2026 payment calendar for lining those dates up.
Open the 2026 payment calendar inside the Social Security Check Protection Kit →
This article was prepared with AI assistance from cited public sources and reviewed before publication.
