After plans leave a county, Medicare Advantage holds up where insurers compete and shrinks where they don't

When Medicare Advantage plans pull out of a county, what happens next tracks how many insurers are left.

We looked at every county where a quarter or more of members lost their plan in 2024, 2025 and 2026, and compared each one with counties that had the same number of insurers but lost almost no plans.

Where eight or more insurers competed, enrollment a year later was about the same as in those comparable counties, 1% lower. Other plans picked people up. With five to seven insurers it was 4% lower. With three or four, 10% lower. With one or two, 26% lower.

CMS's own county data point the same way: Medicare Advantage's share of everyone on Medicare fell 10 points more in the one-or-two-insurer counties, and it was flat the year before the plans left.

This is mostly a rural story. In bigger counties the gap nearly disappears.

For 2027, 109 counties with four or fewer insurers are set to lose a quarter or more of their members' plans. About 406,000 people live in them, most in Minnesota, Florida and Idaho.

It compares similar counties; it is not an experiment. 2027 is our estimate until CMS posts the crosswalk in October. Check your county in our MCP: vladahealth.com/data-access