On October 14 at about 8:30 a.m. Eastern, the Social Security Administration announces the 2027 cost-of-living adjustment. Weeks later, CMS announces the 2027 Medicare Part B premium. Most coverage treats these as two separate headlines. For the roughly half of Social Security recipients who have Part B deducted from their check, they are one number — and they are not the same kind of number.
One Is a Rate. The Other Is a Price.
The COLA is a percentage. It scales with the size of your benefit. The standard Part B premium is a flat dollar amount, identical for every enrollee who isn't paying an income surcharge.
That asymmetry is the whole story. A fixed dollar increase takes a fixed bite out of a raise that varies enormously from retiree to retiree.
Here are the current inputs. The Senior Citizens League projects a 3.5% COLA, trimmed from 3.6% after the August CPI report landed September 11. AARP projects 3.6%. On the premium side, the 2026 Medicare Trustees Report projects the standard Part B premium rising from $202.90 to roughly $209.50 — an increase of $6.60 a month. Private forecasters put it at $216 to $219, or $13.10 to $16.10.
The Same $6.60 Is Not the Same $6.60
Applying a 3.5% COLA to three monthly benefit levels, and asking what share of the raise the premium consumes:
| Monthly benefit | 3.5% raise | If Part B rises $6.60 | If Part B rises $16.10 |
|---|---|---|---|
| $2,000 | +$70.00 | 9% of the raise | 23% of the raise |
| $1,100 | +$38.50 | 17% of the raise | 42% of the raise |
| $800 | +$28.00 | 24% of the raise | 58% of the raise |
The retiree who needs the raise most keeps the least of it. Nothing about that is an accident or a glitch — it falls directly out of dividing a flat number by a proportional one.
Treat the Trustees' Figure as a Floor
The Trustees Report is a projection by actuaries in the spring, not the final rate. In 2021 those actuaries projected a 2022 Part B premium of $158.50. CMS finalized $170.10 — nearly $12 higher, driven partly by reserves set aside for the Alzheimer's drug Aduhelm. Official 2027 figures don't arrive until late this year.
Hold Harmless Probably Won't Help — and May Not Cover You
The hold harmless provision caps your Part B increase at the dollar amount of your COLA, so your net check never shrinks. Two limits matter.
First, it only binds when the premium increase exceeds your COLA dollars. At 3.5%, almost every benefit level clears even the high-end $16.10 estimate — which is why the provision wasn't widely necessary in 2025 or 2026 either.
Second, roughly 30% of enrollees are never protected: those new to Medicare, those whose premiums aren't deducted from a Social Security check, IRMAA payers, and those whose premiums Medicaid pays. It also never covers the Part B deductible or late-enrollment penalties.
Practical Takeaways
- Budget from net, not gross. October 14 gives you half the equation. Your exact 2027 figure arrives in SSA's personalized notice in early December — wait for it before committing to spending.
- Enrolling in Medicare in 2027, or not yet claiming Social Security? You have no floor. You pay the full standard premium whatever it turns out to be.
- If you pay IRMAA, your surcharge is a multiple of the standard premium. Any miss in the standard figure scales up in your bracket.
Sources: 2026 Medicare Trustees Report (via MyFederalRetirement); The Senior Citizens League, "TSCL Predicts COLA at 3.5% With One Month to Announcement"; AARP, 2027 COLA estimate (Rich Johnson, AARP Public Policy Institute); Medicare Rights Center / Medicare Interactive, "Increases in Part B premiums and the hold harmless provision"; medicareresources.org hold harmless FAQ; Kiplinger, "Medicare Part B Premium Jumps Dramatically for 2022"; Yahoo Finance, "Medicare's 2027 Part B Premium Is Projected to Push Past $215 a Month".