Trends in Plan Offerings, Enrollment, and Premiums in Medicare Advantage and Medigap

Examine trends in Medicare Advantage (MA) and Medigap plan offerings, enrollment, and premiums across state regulatory regimes.

We used national data between 2014 and 2021 on MA and Medigap plan offerings, enrollment, and premiums. Data on Medigap plan offerings and premiums were acquired from Weiss Ratings and matched with county-level data on the Medicare population from 2014 to 2021 Medicare Regional Variation and MA Landscape files. States were classified into three groups based on Medigap regulations: community rating and guaranteed issue states (Connecticut and New York); community rating-only states (Arkansas, Maine, Vermont, and Washington); and no additional Medigap regulation states (remaining states).

We considered only MA plans offering prescription drug coverage. Premiums for Traditional Medicare beneficiaries included Medigap and prescription drug premiums and were calculated using an inflation-adjusted Paasche price index to account for variation across plan types and market segments.

Between 2014 and 2021, Medigap offerings and enrollment were relatively constant, while MA enrollment increased substantially. Medigap offerings were lower and MA offerings were higher in states with community rating and guaranteed issue. Between 2014 and 2021, Medigap premiums increased modestly from $4462 to $4745 in states with no additional Medigap regulations and from $6099 to $6612 in states with community rating and guaranteed issue. MA premiums (increased slightly from $2055 to $2121) in states with no additional Medigap regulations and were similar for other states.

Despite modest changes in recent years, Medigap premiums were substantially higher than those of MA. Medigap offerings and enrollment are lower, and premiums are higher, in states with guaranteed issue and community ratings. Nuanced reforms are needed to reduce supplemental insurance costs in Traditional Medicare while preventing adverse selection in Medigap markets.