Updated October 16, 2026. Quick answer. The “hold harmless” rule protects
most Social Security recipients from having their check shrink because Medicare Part B’s
premium rose faster than their COLA — but it does not protect everyone, and it does not
mean your net increase equals the full COLA percentage. Three groups are excluded entirely:
people newly enrolling in Part B, anyone who pays Part B directly rather than having it deducted
from a Social Security check, and anyone who pays the income-related IRMAA surcharge.
Hold harmless (Social Security Act §1839(f)) guarantees that your Social Security check
cannot go down in dollar terms because of a Part B premium increase — if the dollar
increase in your Part B premium would exceed your dollar increase from the COLA, the premium
increase is capped at whatever leaves your check unchanged. It says nothing about your check
going up less than the full COLA; it only stops it from going down.
Who is not covered
New Medicare enrollees. If you first enroll in Part B during 2027, no December 2026 premium is deducted from your benefit, so you are
not protected by hold harmless for the 2027 premium change — you pay the full increase.
Anyone billed directly by CMS. If your Part B premium isn’t deducted from a
Social Security check (because you haven’t claimed benefits yet, or you pay Medicare directly),
hold harmless doesn’t apply — there’s no check for it to protect.
IRMAA payers. If your income triggers the income-related surcharge (in 2026 that starts above
$109,000 single / $218,000 joint of 2024 income; the 2027 thresholds, applied to your 2025 income, are not announced yet — see
the 2027 IRMAA brackets), hold harmless does not apply to you at all, so
your whole premium is exposed to the increase.
Hold harmless is decided in a two-month window, and the calendar is the part that trips people up. The statute is one sentence with three tests in it, all of them dated. What it compares is not two premiums but two checks — and as CMS puts it in the notice that set the 2026 premium, “a benefit check for November is not received until December, but December’s Part B premium has been deducted from it.” So the comparison runs between the payment that arrives in December and the one that arrives in January, each net of its own premium. When the tests are met, CMS applies the protection for that January “and for each of the succeeding 11 months” — it holds for the whole year, not one payment. The three groups this page names as excluded each fail one of these tests, which is where the exclusions come from. CC BY 4.0.
The net-check math, worked through
Say your 2026 benefit is $2,200/month and the 2027 COLA is the announced 3.6%, a $79.20 increase.
If your Part B premium rises from $202.90 to a projected $209.50 to $219, that’s a $6.60 to
$16.10 increase. For a hold-harmless-protected recipient, the premium increase can never exceed
the COLA dollar increase, so the check still rises — just by less than the full 3.6% once
the premium is netted out. An IRMAA payer or new enrollee sees the full premium increase land on
top, with no such floor.
The protection matters enormously in some years and almost not at all in others — and which kind of year it is turns on the COLA. Each row is the announced Part B standard-premium increase divided by the announced COLA: the monthly benefit at which a dollar of premium increase exactly eats a dollar of raise, and so the level below which §1395r(f) held the increase down. In 8 of these 17 years that level sat between $54 and $639 a month, well under most benefits, and in 5 more the standard premium did not rise at all, so there was nothing to cap. But in the 3 years drawn full width the COLA was 0.0% and there was no dollar increase to cap against at all, and in 2017 a 0.3% COLA against a $12.20 premium rise put the level at $4,067 — above almost every benefit in the country. CMS’s own notices confirm both: approximately 70% of Part B enrollees were held harmless for 2017, and for 2016 “the majority of Part B enrollees were held harmless and paid a premium of $104.90” instead of the $121.80 standard. Two honest limits. This is arithmetic on the standard premium, so someone already held harmless from an earlier year faces a different increase of their own. And nothing is plotted for 2027: the COLA is announced at 3.6% (SSA, October 14, 2026) but the premium is not, so the row stays open until CMS announces it. On the premium projections this site publishes, $209.50 (Medicare Trustees) to $219 (private forecasters) against 2026’s $202.90, the level would land near $183 to $447 (the premium increase of $6.60 to $16.10 divided by 0.036). CC BY 4.0.
Sources
Social Security Act §1839(f) (the statutory hold-harmless provision). Premium figures:
see the 2027 Part B premium projections, attributed and not yet
official, and the 2027 COLA, which SSA announced at 3.6% on October 14, 2026. Verified against 42 U.S.C. §1395r(f), CMS Federal Register notice 2025-20251 and SSA’s Federal Register COLA notices on September 29, 2026.
The 2027 COLA on this page is the 3.6% SSA announced on October 14, 2026. The Part B premium figures above are projections attributed to the organization that published them and are not yet announced by CMS; this page will be updated with the official premium the day CMS announces it. See the full current-numbers register for every figure this site tracks, dated and sourced. General information, not tax or legal advice.
Whether hold-harmless bites in 2027 turns on two figures: the COLA, which SSA set at 3.6% on October 14, 2026, and the Part B premium, which CMS has not yet announced. Your 2027 numbers tracks what is already settled for 2027 and when each of these two is published.
