The two changes arrive separately
SSA announces the COLA in October. CMS announces the next year's Part B premium in November. If your Part B premium is deducted from your Social Security payment, your net deposit reflects both. Your December notice from SSA shows the new gross benefit, the premium taken out, and the net amount.
An example (projected)
| 2026 | 2027 (projected) | |
|---|---|---|
| Gross monthly benefit | $2,000 | $2,072 (after 3.6% COLA) |
| Part B premium deducted | $202.90 | $209.50 (Trustees estimate, not final) |
| Net deposit | $1,797.10 | $1,862.50 |
| Change in net deposit | +$65.40 |
The 2027 Part B premium is an estimate until CMS announces it, usually in mid-November.
What the hold harmless rule does
The hold harmless provision says that, for most people who have the Part B premium deducted from Social Security, the premium increase cannot be more than the dollar amount of the COLA. In other words, your net Social Security payment cannot go down from one year to the next because of a Part B premium increase.
Who is not protected
- People who enroll in Part B for the first time in the new year
- People who pay an income-related surcharge (IRMAA)
- People who do not have the premium deducted from their benefit and are billed directly
- People whose state pays their premium through a Medicare Savings Program
Does it matter in 2027?
With a 3.6% COLA, a Part B increase of about $6.60 would be fully covered by the COLA for anyone with a benefit above roughly $183 a month. So for nearly everyone, the hold harmless rule is unlikely to limit the increase in 2027. It matters most in years when the COLA is small and the premium jumps sharply.