Open enrollment is the yearly window when employees can join, drop, or change coverage without a qualifying event. Employer plan windows are set by the employer, while the individual market has its own annual period.
On the federal Marketplace (HealthCare.gov), Open Enrollment runs November 1 to December 15 starting with plan year 2027; earlier years ran into January. Outside it, you generally need a Special Enrollment Period.
Open enrollment is the once-a-year window when you can enroll in or change your coverage. A special enrollment period (SEP) lets you enroll outside that window after a qualifying life event, such as marriage, a new baby, or losing other coverage, usually within 30 days (employer plans) or 60 days (the Marketplace).