Where the 2027 Estimate Sits Today
Two of the most-watched independent forecasts released updated projections in mid-July 2026. The Senior Citizens League (TSCL) held its estimate for the 2027 Social Security cost-of-living adjustment at 3.8%, while independent policy analyst Mary Johnson trimmed hers to 3.7%. Both figures cooled from earlier spring peaks after the June Consumer Price Index came in at 3.5% year-over-year, down from 4.2% a month earlier.
For context, the COLA that took effect in January 2026 was 2.8%. If the current estimates hold, retirees would see a meaningfully larger increase in their January 2027 checks. On the average retired-worker benefit of roughly $1,938 per month, a 3.8% adjustment would add about $74 per month, lifting the typical check to roughly $2,011.
How the Number Is Actually Set
The COLA is not a forecast — it is a formula. Every October, the Social Security Administration averages the CPI-W (Consumer Price Index for Urban Wage Earners and Clerical Workers) for July, August, and September, then compares that average to the same three-month average from the prior year. The percentage change becomes the following January's adjustment.
That means the June inflation reading is not in the calculation. Only the July, August, and September 2026 CPI-W reports determine the official 2027 COLA, which SSA typically announces around October 10–15. A single hot or cool month during that window can move the final figure by tenths of a percentage point.
The CPI-W tracks a basket of goods and services — food, energy, shelter, medical care, transportation — weighted for households where at least half of income comes from wage or clerical jobs. Critics have long argued this basket understates the spending patterns of retirees, who allocate more to healthcare and housing.
The Medicare Part B Offset
Any COLA discussion for Medicare-enrolled retirees has to account for the Part B premium, which is typically deducted directly from Social Security payments. The 2026 Medicare Trustees Report offers competing projections for 2027:
- A more conservative scenario puts the standard Part B premium at $209.50 per month, up $6.60 (about 3.25%) from 2026's $202.90.
- A higher scenario projects $218.60, up $15.70 from 2026.
Under the higher-premium scenario, roughly $15.70 of the average $74 monthly COLA gain would be absorbed by the Part B increase, leaving a net raise closer to $58 per month for retirees enrolled in traditional Medicare. Under the lower scenario, retirees keep substantially more.
Here is what makes 2027 notable: if the final COLA lands near 3.8% and Part B rises at the lower projected pace of 3.25%, it would be one of the rare years since 2023 in which the Social Security adjustment outpaces the Medicare premium hike on a percentage basis. In most recent years, Part B growth has quietly clawed back a large share of the raise.
Practical Takeaways Before October
- Wait for the official number. Estimates from independent analysts are useful, but the July–September CPI-W prints will move the final figure. Do not lock in 2027 budgeting assumptions before SSA's October announcement.
- Watch the Part B announcement separately. CMS typically confirms the standard Part B premium in November. That release, combined with the final COLA, determines the net change hitting your January deposit.
- Model the IRMAA thresholds. Higher-income retirees pay Medicare surcharges based on modified adjusted gross income from two years prior. A 2025 Roth conversion or capital-gain realization could push 2027 premiums well above the standard $209.50–$218.60 figures, wiping out the COLA entirely for affected households.
- Reassess withdrawal plans. A 3.7%–3.8% COLA still likely trails the real cost inflation many retirees face in healthcare and shelter. Investors relying on portfolio withdrawals to supplement Social Security may want to revisit their inflation assumptions before year-end rebalancing.
- Do not overreact to monthly CPI swings. The June reading was a single data point. The COLA formula smooths three months of data, which limits both upside and downside surprises from any one report.
For retirees whose entire income floor sits on Social Security plus Medicare, 2027 is shaping up to deliver something modestly encouraging: a raise that, for once, may not be quietly eaten by the premium hike that follows it.
Sources: The Senior Citizens League – COLA Watch (July 14, 2026 release); Kiplinger – Latest Inflation Data Keeps 2027 Social Security COLA Forecast Steady; CNBC – Social Security COLA in 2027: Cooling Inflation Lowers Estimate (July 2026); The Motley Fool – What a Bigger 2027 COLA Could Mean for Your Medicare Premiums; Medicare Trustees Report 2026 – Part B Premium Projections; Social Security Administration – 2026 COLA Fact Sheet.