Every September, the same ritual plays out: retirement-focused publications start estimating next year's Social Security cost-of-living adjustment weeks before the government makes it official. This year, AARP is projecting a 3.6% COLA for 2027, while the Senior Citizens League has floated a figure around 3.5% — enough to add roughly $73 to the average monthly retirement benefit, which stood near $2,086 as of this past July.
The Social Security Administration will announce the actual, binding number on October 14, at 8:30 a.m. Eastern. Everything published before that date — including this article — is an estimate built on partial data, not the figure that determines your January payment.
What actually sets the number
The COLA isn't a policy decision or a negotiation. It's a formula: the percentage change in the Consumer Price Index for Urban Wage Earners and Clerical Workers (CPI-W) from the third quarter of the prior year to the third quarter of the current year. That means the calculation literally cannot be finalized until September's inflation data is in — which is exactly why every estimate published in September carries the same disclaimer.
AARP's vice president for financial security, Rich Johnson, put it plainly: "Unless prices change dramatically in September, we're confident that the COLA will be in the mid-3 percent range." That's a reasonably confident forecast, not a promise. A single volatile month of energy or shelter costs has moved these estimates before.
The part the estimate doesn't capture
A COLA increase and a Medicare Part B premium increase are announced separately, and for beneficiaries who have Part B premiums withheld directly from their Social Security check, the two numbers interact whether anyone plans for it or not. A rising Part B premium doesn't cancel a COLA, but it quietly reduces how much of the headline percentage actually reaches a retiree's bank account. The 2027 Part B premium hasn't been announced yet — it typically follows in November — so the honest answer this month is that nobody outside the agencies involved knows the net effect yet.
What this means if you're already claiming
- Don't budget hard against the estimate. Mid-3% is a reasonable planning range, but the difference between 3.5% and a lower or higher official number is real money over a full year. Wait for the October 14 announcement before treating next year's benefit as fixed.
- Watch for your COLA notice in December. The SSA sends personalized notices showing the exact new benefit amount and any Part B withholding — that notice, not a September estimate, is the number to plan around.
- Remember the one-month lag. The COLA technically applies to December, but because of how Social Security payments are dated, most beneficiaries don't see the increase reflected until their January payment.
What this means if you haven't claimed yet
If you're still years from claiming, the COLA headline is mostly noise. What matters more for your own plan is the underlying pattern it represents: Social Security benefits are inflation-linked, but modestly and with a lag, which is one reason planners generally treat Social Security as one leg of a retirement plan rather than the whole structure. The accounts you control directly — a 401(k), an IRA, an HSA — don't wait on a government formula to keep pace with your own cost of living.
The patient-investor takeaway
A COLA estimate is useful context, not a planning input. The number worth acting on is the one the SSA confirms on October 14 — and even then, the more durable move is the same one that applies to every other headline number in this newsletter: keep contributing to the accounts you control, let the formulas you don't control do what they're going to do, and update your actual budget once the actual number exists.