Health insurance open enrolment: what it is and why missing it matters
Open enrolment is the annual window during which you can join, change, or leave a health insurance plan without a qualifying life event. Missing it can leave you locked into a plan — or uninsured — for the rest of the year.
What open enrolment is and why it exists
Health insurance markets use open enrolment windows to prevent adverse selection — the tendency for people to buy cover only when they know they need it. If anyone could join or leave a plan at any time, healthier people would exit when well and rejoin when sick, destabilising the risk pool and pushing premiums up for everyone who stayed.
By restricting switching to a defined annual window, open enrolment keeps the risk pool stable and premiums more predictable. The same principle applies to employer-sponsored plans, Medicare Advantage, and state-level exchanges.
Key open enrolment windows by market
Dates above are indicative. Always check the official source for the current year's exact dates, as they can shift by a few days and vary by state exchange.
Open enrolment checklist
Before the window closes, check each of the following:
- Has your premium changed? Most plans increase at renewal — compare the new cost against alternatives.
- Is your deductible still appropriate for your likely usage? A high-deductible plan saves on premiums but costs more when you claim.
- Are your preferred doctors and hospitals still in-network? Networks change annually. See our guide to provider networks.
- Are your regular prescriptions still covered on the formulary (drug list)?
- Has your household income changed in a way that might affect your subsidy eligibility?
Use our yearly cost calculator to model your total expected cost — premium plus likely out-of-pocket — across two or three plan options before deciding.
Open enrolment FAQ
Frequently asked questions
- For Marketplace plans under the Affordable Care Act, the federal open enrolment period typically runs from 1 November to 15 January. Some states with their own exchanges set different dates. For employer-sponsored plans, enrolment windows vary by employer — often in October or November. Check HealthCare.gov for the current federal window and your state exchange for local dates.
- A special enrolment period (SEP) allows you to join or change a health plan outside the standard open enrolment window after a qualifying life event. Qualifying events typically include: losing existing health coverage, getting married or divorced, having or adopting a child, moving to a new coverage area, and certain changes in income that affect your eligibility. You usually have 30 to 60 days after the event to enrol. See HealthCare.gov's special enrolment guidance for the full list.
- In most regulated health insurance markets, no. Outside open enrolment and without a qualifying event, you are generally locked into your current plan or left without cover until the next enrolment window. This is why reviewing your plan during open enrolment — even if you plan to stay — is important: your circumstances, your premium, and your plan's network may all have changed since last year.
- Compare plans on four dimensions: the monthly premium, the annual deductible, the out-of-pocket maximum, and the provider network. Our guide to deductibles and out-of-pocket maximums shows how to calculate your likely total yearly cost under different claim scenarios — which is often more useful than comparing premiums alone. Also check whether your preferred doctors and hospitals are in-network.