It depends on whether there's a Social Security cost-of-living adjustment. Thinkstock By Kimberly Lankford, Contributing Editor From Kiplinger's Personal Finance, March 2016 I'm paying $121.80 per month for Medicare Part B because I haven't yet signed up for Social Security. What will happen to my rates in 2017 if I sign up for Social Security benefits this year? --B.W., Ellicott City, Md.See Also: When to Sign Up for Medicare Coverage That depends on whether there's a Social Security cost-of-living adjustment next year. Because there was no COLA for 2016, most people did not see a hike in Medicare Part B and continue to pay $104.90 per month. (If there is an increase in Medicare premiums, the "hold harmless provision" prohibits Social Security benefits from being reduced for anyone who has Medicare premiums paid from their benefit check.) But people who don't receive Social Security benefits or who sign up for Medicare in 2016 pay $121.80 per month, including $3 extra per month to help cover this year's shortfall. You pay more if your modified adjusted gross income is more than $85,000 for single filers or $170,000 for joint filers. If there is a Social Security COLA for 2017, everyone who isn't subject to the high-income surcharge could pay the same premium, which will be determined by actual health care costs, plus the extra $3. If there is no COLA for 2017, there could be three tiers of premiums (not counting the high-income surcharge), says Juliette Cubanski, of the Kaiser Family Foundation. See Also: Navigating Medicare Special Report Got a question? Ask Kim at firstname.lastname@example.org.