A retiree who received the 2.8% Social Security cost-of-living adjustment for 2026 already knows the drill: some of that raise disappeared into a bigger Medicare Part B premium before the first check hit the bank. The 2026 Medicare Trustees Report projects a 2027 standard Part B premium of $209.50 a month, up from $202.90 in 2026. That is only a projection, and recent history shows why retirees should not treat it as the final number.
For people already on Medicare or about to enroll, the Part B premium is one of the fixed costs that shapes every monthly benefit check. The exact 2027 number is not final yet, but the planning issue is already clear: even a modest premium increase can eat into the next Social Security raise.
What the trustees actually said, and why $215 is in play
The 2026 Medicare Trustees Report projects a $209.50 standard Part B premium for 2027, up from $202.90 in 2026. That would be a 3.25% increase, much smaller than the 9.7% jump from 2025 to 2026. The trustees also projected longer-term increases, including $224.50 in 2028 and $338.50 by 2034.
Trustee projections are not final premium notices. In 2021, the trustees projected a 2022 standard Part B premium of $158.50, but CMS later finalized the 2022 premium at $170.10 after accounting for Aduhelm and other spending assumptions. Applying a 6% increase to the 2026 premium would put 2027 near $215. That is not CMS guidance, but it shows why the final number could land above the trustee baseline.
For a retiree receiving the average retired-worker benefit, SSA estimated the 2026 COLA raised the monthly check from $2,015 to $2,071. The difference between a $209.50 Part B premium and a $216 premium is $6.50 a month, or $78 a year. That is not a budget-breaker by itself, but it shows how small Medicare changes can keep nibbling at a COLA.
How the raise gets eaten
The Social Security COLA is based on CPI-W, and the 2027 COLA will not be announced until October 2026. The Part B premium is set through a separate Medicare process tied to expected program costs. If the final Part B increase runs ahead of the COLA, the gap will reduce the raise retirees actually feel in their monthly checks.
Two structural traps compound the problem:
- The auto-renewal trap. A beneficiary who does nothing during the October 15 to December 7 open enrollment period is re-enrolled in the same Medicare Advantage or Part D plan, whose formulary, pharmacy network, and copay tiers may have shifted. Re-shop every year.
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Indexing that does not protect everyone equally. Most IRMAA income brackets adjust for inflation, but the highest tier still begins at $500,000 for individuals and $750,000 for joint filers in the 2026 table. A household with a one-time income spike, or income that rises faster than the lower brackets, can still drift into a higher tier.
Who actually pays the IRMAA surcharge
IRMAA hits roughly 8% of Part B enrollees. The 2027 IRMAA thresholds have not been finalized yet, but the 2026 thresholds begin above $109,000 for single filers and $218,000 for joint filers. The 2027 surcharge will generally be based on 2025 modified adjusted gross income.
For those above the threshold, the 2026 Part B surcharges run from $81.20 a month at the first tier to $487 a month at the top, producing a total Part B premium of $689.90 for the highest earners. Part D IRMAA adds another $14.50 to $91 per month on top of the drug plan premium. The determination generally uses a two-year lookback: 2025 income drives 2027 premiums, and 2026 income drives 2028 premiums.
MAGI for this test is Form 1040 line 11 plus tax-exempt interest from line 2a. Municipal bond income that feels tax-free still counts. A Roth conversion or large capital gain can push a household up a tier before they realize it. SSA-44 relief is limited to qualifying life-changing events, including marriage, divorce or annulment, death of a spouse, work stoppage, work reduction, certain losses of income-producing property, loss of pension income, and an employer settlement payment. A voluntary Roth conversion or voluntary home sale does not qualify by itself.
What to do before January
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Confirm the MAGI on the tax return Social Security is likely to use. For 2027 premiums, that generally means your 2025 tax return. If the income is already on that return, a 2026 year-end distribution decision will not change the 2027 IRMAA result, though it can still affect 2028.
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Re-shop Part D and Medicare Advantage during the October 15 to December 7 open enrollment period. The premium you notice is Part B, but drug formularies, pharmacy networks, copay tiers, and plan rules can change each year.
- If you had a qualifying life-changing event in 2025 or 2026 that reduced your income, request a new IRMAA determination with SSA-44. Attach documentation for the event and the lower MAGI. Do not assume a voluntary Roth conversion, capital gain, or home sale can be reversed through SSA-44.
Do Not Treat the Projection as the Bill
The trustee projection gives retirees a useful starting point, not a final 2027 premium. The better move is to plan around both possibilities: the baseline near $209.50 and a higher final number if Medicare cost assumptions change before CMS sets the rate. The premium may look like a small monthly line item, but over time it is one of the main ways health costs eat into Social Security raises.
Source note: 2026 premium, deductible, and IRMAA figures come from the CMS “2026 Medicare Parts A & B Premiums and Deductibles” fact sheet and SSA Form SSA-44. The 2027 Part B premium projection comes from the 2026 Medicare Trustees Report. Social Security COLA and average benefit figures come from SSA’s 2026 COLA fact sheet.
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