The Hold Harmless Rule, Explained
The rule
Section 1839(f) of the Social Security Act: when the standard Part B premium rises, the increase charged to a protected beneficiary cannot exceed the dollar amount by which their benefit rose under that year's COLA. The protection has been in place since the late 1980s and is applied automatically — there is no application, and your December COLA notice simply reflects the capped premium if it applies to you.
Worked example, 2027
Take a small check of $180 a month. The 3.6% COLA raises it by $6, to $186. The standard premium is projected to rise by $6.60 ($202.90 in 2026 → $209.50 in 2027, a projection until CMS announces). Without protection, the premium would take the whole raise and $0.60 more — the net check would fall. With hold harmless, the premium increase is capped at the $6 raise: the premium becomes $208.90 instead of $209.50, and the net check stays exactly flat instead of dropping. That is the entire mechanism — a cap on the increase, not a discount on the premium.
With the 2027 numbers, the rule only binds for checks under about $183, because the projected premium rise is small. Its starring years were the zero-COLA years: in 2010, 2011 and 2016, with no raise to absorb any increase, hold harmless froze the premiums of roughly 70% of beneficiaries outright while new and unprotected enrollees paid the full standard rate — the two-tier outcome traced on the Part B premium history page. The net COLA calculator runs this check on your own numbers automatically.
Who is NOT protected
| Group | Why not |
|---|---|
| New Part B enrollees in 2027 | No prior-year premium deducted from a check to cap from — they pay the full standard rate from day one. |
| IRMAA payers | The income-related surcharge tiers sit outside the hold-harmless protection. |
| Medicaid-paid premiums | If a state Medicaid program pays your premium (a Medicare Savings Program), there is no deduction from your check for the rule to protect. |
| Direct payers | People billed by CMS directly — typically those not yet receiving a benefit — are outside the withholding mechanism. |
| Not entitled in Nov–Dec 2026 | Protection requires entitlement to a benefit and Part B enrollment, with withholding, in November and December of the prior year. |
| Federal annuitants without a Social Security check | CSRS retirees whose Part B premium is not deducted from a Social Security benefit do not get the cap — a long-standing asymmetry with the Social Security population (their COLA itself is covered on the federal retiree COLA page). |
Hold harmless also only covers the Part B premium increase — it does not protect against changes in Part D or Medicare Advantage plan premiums, tax withholding changes, or overpayment recoveries, any of which can still move a net deposit.
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Frequently asked questions
What is the hold harmless rule?
A provision of the Social Security Act (§1839(f)) that caps the increase in your Medicare Part B premium at the dollar amount of your COLA raise, when your premium is deducted from your Social Security check. It guarantees that a premium increase, by itself, cannot make your net check smaller.
Am I protected in 2027?
You are generally protected if you were entitled to Social Security benefits and enrolled in Part B in November and December 2026, with the premium withheld from your check. You are not protected if you start Part B in 2027, pay an IRMAA surcharge, have your premium paid by Medicaid, pay the premium directly, or were not receiving a benefit in November–December 2026.
Does hold harmless matter for 2027?
Only at the margin: the projected premium rise is $6.60 a month ($202.90 → $209.50, projection), and a COLA raise is smaller than that only on checks under about $183. For everyone else the 3.6% raise covers the premium rise on its own. The rule's real historical work was in the zero-COLA years — 2010, 2011 and 2016 — when it froze most premiums outright.
If I am held harmless, do I ever catch up?
Yes. Hold harmless is a cap on each year's increase, not a discount: in later years your premium rises toward the standard rate whenever your COLA raise is large enough to absorb the difference. Beneficiaries held harmless in 2016 spent several years converging back to the standard premium.
Sources: Social Security Act §1839(f); SSA and CMS explanations of the hold harmless provision; Medicare Trustees 2027 premium projection (labeled as projection).