Enrollment in Health Insurance

enrollment summaries

Monthly Enrollment Summaries
(through March 2021)

To provide more rapid insight into the impact of COVID-19 on insurance coverage in the Commonwealth, CHIA has produced monthly enrollment data summaries by key market sector. This report series is in addition to CHIA's regular biannual Enrollment Trends reports.

This month’s publication includes enrollment figures through March 2021, including a full year of health insurance enrollment data following Governor Baker’s state of emergency declaration.

Enrollment Trends

Enrollment Trends
(through September 2020)

Additionally, twice a year CHIA updates its detailed Enrollment Trends analysis for the most recent two-year period to give researchers and policymakers insight into the market. This edition, published in March 2021, covers the period between September 2018 and September 2020 and includes breakouts by payer and product type, providing a baseline for enrollment prior to the pandemic. The next Enrollment Trends publication will include detailed data through March 2021.

CHIA’s bi-annual Enrollment Trends reporting includes an interactive dashboard, a detailed databook, and technical appendix. For this reporting, coverage is defined by unique Massachusetts residents with primary, medical membership in the 12 largest commercial payers, MassHealth (Medicaid), or Medicare.

Enrollment measures are also reported in CHIA's Annual Report on the Performance of the Massachusetts Health Care System.


Updated March 2021

Previous Enrollment Publication Materials

2021 Publications

Monthly Enrollment Summaries






Enrollment Trends (through September 2020)
Published March 2021



2020 Publications

Monthly Enrollment Summaries






Enrollment Trends (through March 2020)
Published September 2020


Enrollment Trends (through September 2019)
Published March 2020



2019 Publications

Enrollment Trends (through March 2019)
Published August 2019


Enrollment Trends (through September 2018)
Published February 2019



2018 Publications

Enrollment Trends (through March 2018)
Published August 2018


Enrollment Trends (through September 2017)
Published February 2018



2017 Publications

Enrollment Trends (through March 2017)
Published August 2017


Enrollment Trends (through September 2016)
Published March 2017



2016 Publications

Enrollment Trends (through March 2016)
Published July 2016


Enrollment Trends (through September 2015)
Published February 2016