A time outside of the Open Enrollment Period when you can sign up for health insurance. You qualify for a Special Enrollment Period if you've had certain life events, including losing health coverage, moving, getting married, having a baby, or adopting a child.
If you qualify for an SEP, you usually have up to 60 days following the event to enroll in a plan. If you miss that window, you have to wait until the next Open Enrollment Period to apply. Job-based plans must provide a special enrollment period of at least 30 days.