Normally, the hold harmless provision does not take effect because the COLAs exceed the Medicare premium increases. This year, however, because the COLA is small, 70 percent of Medicare beneficiaries will receive a more limited premium increase (about $4.30 per month for someone receiving the average Social Security benefit) than they otherwise would. But since Medicare premiums must cover one-quarter of the cost of Part B, the remaining 30 percent of beneficiaries are tasked with making up the difference, leading to a large premium increase for them. The Medicare Trustees, working off the assumption that the COLA would be 0.2 percent, estimated that the monthly premium for the unprotected 30 percent would increase from $121.80 to $149, an annual increase of $325. For high-income beneficiaries who pay higher premiums, their annual increase will range from $457 to $1,044. These increases will be a little bit smaller in reality since the actual COLA is slightly higher than the Trustees assumed.