Under Social Security and Medicare rules, the “Hold Harmless” provision is a special rule intended to protect most Social Security recipients from experiencing a decrease in their (net) benefit payments, by limiting the (dollar) amount of the annual Medicare Part B premium increase to the (dollar amount) of Social Security’s cost-of-living adjustment. And due to negative inflation from the recent fall in energy prices, the 2016 Social Security COLA is on tracked to be “floored’ at the minimum 0.0%, which in turn means that Medicare Part B premiums will be locked in for a 0.0% increase in 2016.
However, the "Hold Harmless" provisions only apply to approximately 70% of currently Medicare enrollees for the protection. Which means that the entire magnitude of Medicare's rising costs must be borne by just the other 30% of Medicare enrollees, as well as any who planned to enroll in 2016, resulting in a project 52% spike in Part B premiums next year!
Given the looming Medicare Part B premium increase, those who are not eligible for the Hold Harmless provision - for instance, those enrolled in Medicare but delaying Social Security benefits, or those who haven't yet enrolled in either but could - should carefully consider whether it is really still worth delaying Social Security benefits (and/or delaying enrollment in Medicare), given that those who begin the process by October of this year still have the potential to get started in time to be eligible for Hold Harmless and shelter themselves from the 2016 increase.
And in practice, it appears that slightly accelerating claiming may in fact be appealing, especially for those who otherwise anticipated starting Social Security and Medicare Part B in 2016. On the other hand, higher-income taxpayers who are subject to the Medicare Part B premium surcharge cannot protect themselves (or do anything else about it, since the calculation would be based on income from 2014 and that tax year is long since closed). And for those who still plan to delay Social Security benefits for many years to come, the reality is that delaying Social Security benefits is still so valuable, that even the projected Medicare Part B premium spike is still not nearly enough to deter the long-term value of generating Social Security’s Delayed Retirement Credits for those who anticipate living well past the breakeven period.