Most Massachusetts consumers must buy health insurance during a specific time of year when enrollment in health insurance is open. This open enrollment period is set by state and federal law and changes each year. If you did not purchase health insurance during the last open enrollment period, you may still be eligible to sign up for or enroll in health insurance by requesting a waiver from the Office of Patient Protection (OPP). Please note that the 2021 open enrollment period ended on July 23. The next open enrollment period begins on November 1st.