Short answer: For HealthCare.gov, open enrollment generally runs November 1 to January 15. Enroll by December 15 for coverage starting January 1. Some state-run marketplaces use different dates, and a qualifying life event can open a special enrollment period any time of year.
The individual market has a yearly open enrollment period that is separate from any employer’s. For the federal marketplace (HealthCare.gov), the period has generally run from November 1 through January 15. If you enroll by December 15 your coverage typically starts January 1; if you enroll between December 16 and January 15 it usually starts February 1.
States that run their own marketplaces can set different deadlines, and some extend later than the federal schedule, so check your state’s marketplace. Enrollment rules continue to evolve, and future federal open-enrollment periods are scheduled to end earlier (around December 15), so confirm the current year’s dates before you rely on them.
Outside open enrollment, you can only enroll or change individual coverage if you have a qualifying life event, such as losing other coverage, marriage, birth or adoption, or a move, which opens a special enrollment period, usually 60 days. Medicaid and CHIP, by contrast, are open for enrollment year-round.