The Centers for Medicare and Medicaid Services (CMS) have announced that the standard monthly Part B premium in 2018 will remain $134 (or higher, depending on your income). In 2017, most Medicare beneficiaries who received Social Security benefits paid a lower monthly premium ($109, on average). However, this is likely to change in 2018.
Due to a provision in the Social Security Act called the "hold harmless" rule, Medicare premiums for existing beneficiaries can't increase faster than their Social Security benefits. Over the past few years, Social Security benefits didn't increase much because of low or no cost-of-living increases. However, there will be a 2% cost-of-living increase for Social Security benefits in 2018. This increase will cause more people to pay higher monthly Medicare Part B premiums closer to the standard ($134) amount.