During the yearly Open Enrollment Period, you can enroll in or change a health plan any time. Open enrollment for 2017 health insurance ends January 31, 2017.
Usually, when you enroll by the 15th of the month, your coverage starts the first day of the next month.
Special Enrollment Periods. If you have a life event that qualifies you for a Special Enrollment Period — like losing health coverage, getting married, or having a baby — your coverage can sometimes start sooner than it otherwise would.
Medicaid and the Children’s Health Insurance Program (CHIP). You can apply for free or low-cost coverage through Medicaid and CHIP any time, all year. If you qualify you can enroll immediately.