CMS — Centers for Medicare & Medicaid Services

Definition. The federal agency in the Department of Health and Human Services that administers Medicare and oversees state Medicaid programs, including the Oregon Health Plan.

What it means

CMS sets Medicare's rules and yearly amounts, such as the Part B premium ($202.90 a month in 2026) and the Part A deductible ($1,736 in 2026). It contracts with the private companies that offer Medicare Advantage and Part D plans, publishes plan data and Star Ratings, runs Medicare.gov and 1-800-MEDICARE (1-800-633-4227, TTY 1-877-486-2048), and sets the marketing rules agents and plans must follow. Social Security, not CMS, handles signing up for Medicare and premium questions tied to your Social Security benefit.

Much of this site's Oregon data comes from CMS: plan counts by county from the CMS Landscape files and enrollment counts from CMS monthly enrollment data.