The yearly period when people can enroll in a health insurance plan. Outside the Open Enrollment Period, you generally can enroll in a health insurance plan only if you qualify for a Special Enrollment Period. You qualify if you have certain life events, like getting married, having a baby, or losing other health coverage. Job-based plans may have different Open Enrollment Periods. Check with your employer. You can apply and enroll in Medicaid or the Children’s Health Insurance Program (CHIP) any time of year.

References

https://www.healthcare.gov/glossary/open-enrollment-period/