The cost-of-living increase, which will affect roughly 70 million people starting in late December and January, is tied to a measure of inflation that has surged this year as prices rise in a U.S. economy emerging from the pandemic. Experts caution that millions of seniors will in reality see substantially less than a 6 percent bump, because Medicare Part B premiums are deducted from Social Security beneficiaries’ checks and are tied to seniors’ income. The increase in benefits will amount to roughly an additional $92 per month for seniors.