The Senior Citizens League’s COLA Watch put the 2027 Social Security raise at 3.6% on Aug. 12 — down from 3.8% just a few weeks earlier, and way down from the 4.7% an independent analyst was floating back in June. Cooling inflation keeps doing this. Every fresh CPI report shaves a little more off the number retirees have been mentally spending since spring, and the trend line only points one direction: down.

Here’s the part that makes the shrinking estimate worse than it looks. Whatever number the Social Security Administration announces on Oct. 14, some of it is already spoken for. Medicare Part B premiums are projected to climb to $209.50 a month in 2027, and that premium gets deducted straight out of your Social Security check before it ever reaches your bank account. A smaller raise plus a bigger deduction is not a great combination if you’ve been budgeting off the spring estimates.

Quick Verdict

Latest 2027 COLA estimates (early Sept. 2026)	3.4% (Mary Johnson) to 3.6% (TSCL); AARP puts it at 3.5%
Where estimates started in 2026	As high as 4.7% in June, on a hot May inflation print
2026 COLA (for comparison)	2.8%
Official announcement date	Oct. 14, 2026, using July–September CPI-W data
Medicare Part B premium, 2027 projection	$209.50/month, up from $202.90 in 2026 (+$6.60, ~3.3%)
Who sets that projection	The 2026 Medicare Trustees Report; CMS confirms the real number in November
What to do now	Rebuild your 2027 budget around the current estimate, not the one from three months ago

Why the Estimate Keeps Shrinking

Social Security’s cost-of-living adjustment tracks the CPI-W (the Consumer Price Index for Urban Wage Earners and Clerical Workers), and it’s been drifting lower most of the summer as tariff-driven price spikes from earlier in the year worked their way out of the year-over-year comparison. Mary Johnson, the independent Social Security and Medicare policy analyst whose monthly estimates most retirement writers cite, put her number at 4.7% in June. That was the peak. July’s cooler data pulled her down to 3.7%. As of early September, she’s at 3.4%.

TSCL’s math tells the same story from a different angle. Their model, built on CPI trends, Fed policy, and unemployment data, had the 2027 COLA at 3.8% in July and 3.6% by mid-August. AARP entered the picture for the first time this cycle with its own estimate, landing at 3.5%. Three groups, three different models, and they’ve converged on roughly the same shrinking number. That convergence matters more than any single estimate does. When independent analysts using different methodologies land within two-tenths of a point of each other, the range is probably close to where the real number lands.

None of this means the raise disappears. Even 3.4% beats the 2.8% COLA that took effect this January. It’s just smaller than what the spring headlines promised, and it’s still moving before the number becomes official.

How Is the Social Security COLA Calculated?

The Social Security Administration doesn’t guess or negotiate the COLA. It runs a fixed formula:

1. Take the average CPI-W for July, August, and September of the current year.
2. Compare it to the average CPI-W for the same three months of the prior year.
3. The percentage increase, rounded to the nearest tenth of a point, becomes the COLA, applied to benefits starting with the January payment.
4. If CPI-W doesn’t rise year over year, there’s no COLA at all — it’s happened before, most recently in 2010, 2011, and 2016.

That’s why every estimate before October is still an estimate. Two of the three months that matter (August and September) weren’t even measured yet when TSCL published its 3.6% figure. August’s CPI-W came out Sept. 11, the same week as the jobs and inflation data that’s been moving Fed rate-hike odds. September’s number, and the final COLA, land together on Oct. 14.

When Is the 2027 COLA Announced?

October 14, 2026. That’s the date the Bureau of Labor Statistics releases September’s CPI-W, which completes the three-month average the SSA needs to calculate the raise. The announcement also sets the 2027 maximum taxable earnings base and the retirement earnings test limits for people still working while collecting benefits. It does not set the Medicare Part B premium. That comes from CMS separately, typically in November, after the COLA is already locked in.

The Medicare Part B Problem Nobody Budgets For

Every January, two things happen to a Social Security check at once: the COLA raises the gross benefit, and the new Medicare Part B premium (deducted automatically for anyone enrolled) takes a bite out of it before deposit. Most years the COLA is big enough that nobody notices the second part. This year is closer.

The 2026 Medicare Trustees Report projects the standard Part B premium at $209.50 a month in 2027, up from $202.90 this year, a $6.60 increase of roughly 3.3%. That’s actually the smallest percentage jump since 2023, which sounds like good news until you remember it’s still a bigger number to subtract from an already-shrinking raise. And the Trustees’ baseline might be the optimistic case: private forecasters, pointing to the fact that CMS has undershot its own projections in each of the last two years, put the real 2027 premium closer to $216 to $219. Nothing’s official until CMS confirms it in November, but budgeting off the low number and getting surprised by the high one is exactly the mistake worth avoiding here.

Do the Math: What Does This Actually Leave You With?

Take a $2,000 monthly benefit. Back in July, when TSCL’s estimate still sat at 3.8%, that COLA would have added $76 to the check. Subtract the Part B premium increase ($6.60) and the actual net gain drops to $69.40. That’s roughly an 8.7% haircut off the raise before it hits your account, and that’s using the higher, earlier estimate.

Run the same math on today’s numbers and it gets tighter. A 3.6% COLA on that same $2,000 benefit adds $72; net of the Part B hike, $65.40. At Mary Johnson’s 3.4% estimate, the COLA adds $68, netting $61.40 after Medicare. And if the Part B premium actually lands at $216 instead of $209.50 (the scenario private forecasters are flagging), the Medicare deduction alone wipes out nearly a fifth of even the higher COLA estimate.

The pattern holds at any benefit size: whatever the COLA percentage turns out to be, subtract roughly $6.60 to $13 a month for Medicare before deciding what it actually means for your budget.

What to Do Before Oct. 14

You don’t need the official number to start adjusting. A few things worth doing now:

• Rebuild whatever budget you built off the spring estimates. If you penciled in a 4.7% or even 3.8% raise back when those numbers were circulating, that plan is already out of date. Use 3.4%–3.6% instead, and subtract the Medicare premium before you count the difference as spendable.
• Don’t count on the high end of the Part B range either. Plan around $209.50 as the floor, not the ceiling, given how often CMS has landed above its own Trustees Report projections recently.
• If a rate cut is also on your radar this fall, don’t let savings sit in a low-rate account while you wait for January. Top savings rates have already slipped from near 5% earlier this year, and a comparison of current high-yield savings options is worth fifteen minutes if you’re parking any part of this year’s benefit.
• Tighten the monthly budget now if the gap matters. A budgeting app built for stretched margins can model a $61–$70 monthly swing better than a mental estimate can, especially if healthcare costs are also climbing on your end. Medicare Part B premiums aren’t the only medical cost rising heading into 2027.

The Bottom Line

The 2027 COLA has gone from a headline-grabbing 4.7% in June to a consensus range of 3.4% to 3.6% in September, and it could keep drifting before the Oct. 14 announcement locks it in. That’s still a bigger raise than the 2.8% retirees got this year — just a smaller one than the spring numbers suggested, and one that a projected $6.60 Medicare Part B increase will partially cancel out before it reaches anyone’s bank account. Budget off the current estimate, not the one from three months ago, and treat the Part B premium as a subtraction you make before you decide what the raise is actually worth to you.

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2027 COLA estimates from The Senior Citizens League, AARP, and independent analyst Mary Johnson as reported by The Motley Fool, Sept. 2, 2026. Earlier 2026 estimate history from CNBC, June 12, 2026. Medicare Part B premium projections from the 2026 Medicare Trustees Report as reported by Newsweek and FedTools. Figures reflect data available as of early September 2026; both the COLA and the Part B premium remain estimates until the SSA and CMS confirm them in October and November, respectively.