Social Security COLA 2027 estimates run from 3.4% to 3.6%, and the two United States CPI-W readings already published point to the low end. A September index unchanged from August would produce 3.4%. The Social Security Administration announces the official figure on 14 October 2026.
What the August Reading Locked In
Two of the three months that decide the adjustment are now published, and both came from the US Bureau of Labor Statistics. The cost-of-living adjustment, or COLA, is the annual inflation increase applied to United States Social Security benefits. It applies to US benefits only and has no bearing on state pensions elsewhere.
The measure used is the Consumer Price Index for Urban Wage Earners and Clerical Workers, or CPI-W — a different index from the headline CPI-U that most inflation reporting quotes. In the BLS release published on 11 September 2026, the agency stated that the “Consumer Price Index for Urban Wage Earners and Clerical Workers (CPI-W) increased 3.5 percent over the last 12 months to an index level of 328.481 (1982-84=100)”.
| Month | CPI-W Index (1982-84=100) | 12-Month Change | Published |
|---|---|---|---|
| July 2026 | 327.104 | 3.4% | 12 August 2026 |
| August 2026 | 328.481 | 3.5% | 11 September 2026 |
| September 2026 | Not yet published | Not yet published | 14 October 2026 |
The Social Security Administration averages the July, August and September index values and compares that average with the same quarter of the last year in which a COLA was paid. That base figure is 317.265, the third-quarter 2025 CPI-W average. The result is rounded to the nearest tenth of a percentage point.
What September Has to Do for Each Estimate
With July and August fixed, the September index is the only variable left, and it moves the quarterly average by a third of whatever it moves itself. Applying the published figures to the Social Security Administration’s formula gives the following, before rounding.
| If the September CPI-W Index Is | Quarterly Average | Adjustment Before Rounding |
|---|---|---|
| 328.481 (unchanged from August) | 328.022 | 3.39% |
| 329.523 (up about 0.32% on the month) | 328.369 | 3.50% |
| 330.475 (up about 0.61% on the month) | 328.715 | 3.60% |
In plain terms, a September that simply holds August’s level produces 3.4% after rounding. The 3.5% and 3.6% estimates in circulation both require prices to keep rising through September. Nothing about that is settled: the September reading has not been taken, and the BLS will not publish it until 14 October 2026.
Where the Competing Estimates Come From
The published estimates differ because each organisation fills the September gap differently.
- AARP: 3.6%, on its own estimate page, built from CPI-W data for October 2025 to August 2026 plus Federal Reserve inflation forecasts for September.
- The Senior Citizens League: 3.5%, published on 11 September 2026, which the group said was 0.1 percentage points below its August projection.
- MyFederalRetirement: 3.5%, from a single-month calculation of the August index against the 2025 base, updated 11 September 2026.
None is the official figure, and each is revised monthly. Federal retirees should note a separate rule: when the Social Security and CSRS adjustment exceeds 3%, the Federal Employees Retirement System version is that figure minus one percentage point, which would make a 3.5% COLA a 2.5% FERS increase.
What It Is Worth in Dollars
The average monthly benefit for a retired worker in the United States stood at $2,071 in January 2026, according to Social Security Administration data. AARP calculates that its projected 3.6% adjustment would add about $75 a month, taking the average to roughly $2,146. At 3.4% the same average would rise by about $70.
No individual receives the average. The COLA is a percentage applied to each beneficiary’s own benefit, so a smaller payment produces a smaller dollar increase and a larger payment a larger one. For comparison, the 2026 COLA of 2.8% added about $56 a month, lifting the average from $2,015 to $2,071.
Rich Johnson, vice-president for financial security at AARP’s Public Policy Institute, framed the value of early estimates in terms of planning rather than certainty: “The sooner we provide reliable information about benefit increases, the sooner people can start planning.”
The Medicare Premium That Lands Afterwards
The COLA and the Medicare Part B premium are decided separately, on different timetables, and the second can absorb part of the first. Part B is the portion of US Medicare covering doctor visits and outpatient care, and its standard premium is usually deducted from Social Security payments.
The standard Part B premium is $202.90 a month in 2026. The 2026 Medicare Trustees Report projects $209.50 for 2027, an increase of $6.60. That is a projection, not a decision: the Centers for Medicare and Medicaid Services normally confirms the following year’s premium in November.
Against an estimated increase of $70 to $75 a month, a $6.60 premium rise would leave most of the adjustment intact, unlike years when a steeper Part B increase consumed a larger share. The hold harmless provision, which stops a Part B rise from cutting a beneficiary’s net payment below the previous year’s, would still matter for those whose own dollar COLA is smaller than the premium increase.
The Dates That Settle It
- Tuesday 14 October 2026: The BLS publishes September CPI data and the Social Security Administration announces the official 2027 COLA the same day.
- November 2026: The Centers for Medicare and Medicaid Services is expected to confirm the 2027 Part B premium, deductible and income-related surcharge brackets.
- January 2027: The adjustment takes effect with that month’s payments.
The August inflation release that produced these figures also moved expectations for US monetary policy, as set out in this site’s report on how the August CPI report lifted Fed hike odds.
Frequently Asked Questions
What Is the Social Security COLA for 2027?
It has not been set. On the July and August 2026 CPI-W readings, a flat September would produce 3.4%. AARP estimates 3.6% and The Senior Citizens League 3.5%. The Social Security Administration announces the official figure on 14 October 2026.
How Is the Social Security COLA Calculated?
The Social Security Administration averages the CPI-W index for July, August and September, compares it with the same quarter of the last year a COLA was paid — 317.265 for third-quarter 2025 — and rounds the percentage change to the nearest tenth of a point.
When Will the 2027 COLA Be Announced?
On 14 October 2026, the same day the US Bureau of Labor Statistics publishes September inflation data. The increase applies to payments from January 2027.
How Much More Would the Average Benefit Pay?
The average US retired-worker benefit was $2,071 a month in January 2026. AARP calculates that a 3.6% adjustment would add about $75 a month; a 3.4% adjustment would add about $70. Individual increases depend on each beneficiary’s own benefit amount.
Will the Medicare Part B Premium Cancel Out the Increase?
Not on current projections. The 2026 Medicare Trustees Report projects a $6.60 rise in the standard Part B premium for 2027, to $209.50 from $202.90. The Centers for Medicare and Medicaid Services normally confirms the actual figure in November.
