“Open enrollment” is four different calendars wearing the same name. There is the Affordable Care Act Marketplace window, a separate window your employer picks, a Medicare window that opens two weeks earlier and closes six weeks sooner, and a set of state marketplaces that ignore the federal dates entirely.
Miss the right one and you are usually locked out for a year. This page lays out all four, plus the coverage start rule that trips up more people than any deadline does. Every date below was pulled on September 6, 2026 from the agency or marketplace that sets it.
HealthCare.gov: November 1, 2026 to January 15, 2027
For 2027 coverage in every state that uses the federal platform, open enrollment runs November 1, 2026 through January 15, 2027.
CMS stated those dates in a document dated July 27, 2026, writing that open enrollment at the Federally-facilitated Marketplace “will begin on November 1, 2026 and end on January 15, 2027.” A second CMS statement dated August 4, 2026 repeated them. HealthCare.gov’s dates and deadlines page shows the same window.
Two dates inside that window matter more than the endpoints:
- December 15, 2026 is the last day to enroll or change plans for coverage starting January 1, 2027.
- January 15, 2027 is the last day to enroll at all. Plans selected between December 16 and January 15 start February 1.
After January 15 you need a special enrollment period. Medicaid and CHIP are the exception; HealthCare.gov notes you can apply for those any time of year.
Why the Rulebook and the Calendar Disagree Right Now
If you have seen headlines saying open enrollment now ends December 15 or December 31, they are describing a regulation that is not currently being enforced. Both statements are true at the same time, and it is worth understanding why.
The HHS Marketplace Integrity and Affordability final rule, published at 90 FR 27074 on June 25, 2025, added a new paragraph to the enrollment regulation. As printed, 45 CFR 155.410(e)(5) says that for benefit years beginning on or after January 1, 2027, the annual open enrollment period “must begin no later than November 1 and must end no later than December 31 of the calendar year preceding the benefit year,” and “must not exceed 9 weeks in duration.” In the rule’s preamble, CMS said that beginning with 2027 the federal-platform dates would be November 1 through December 15.
That provision was challenged. In City of Columbus v. Kennedy, the U.S. District Court for the District of Maryland struck several parts of the rule on June 12, 2026 and stayed parts of the 2027 payment notice on July 16, 2026. In its July 27, 2026 statement, CMS said it “has not altered the dates for the Open Enrollment period contained in 45 CFR 155.410(e)(4),” the older paragraph that produces the November 1 to January 15 window.
The government has appealed. Georgetown Law’s Health Care Litigation Tracker lists the case in the Fourth Circuit with oral argument set for October 30, 2026.
What to do about it: follow the CMS and HealthCare.gov dates, which are what the Marketplace will actually run on. But do not treat January 15 as a safety net. If the appellate court reinstates the shortened window mid-season, the operative deadline could move. Enrolling by December 15 protects you either way, and it is the only date that gets you January 1 coverage.
State Marketplaces Run Their Own Calendars
About twenty states plus the District of Columbia run their own marketplaces, and several of them do not use the federal dates. Below are the windows published by the marketplaces themselves as of September 6, 2026.
| Marketplace | Open enrollment window | Note |
|---|---|---|
| HealthCare.gov (federal platform) | Nov 1, 2026 to Jan 15, 2027 | Dec 15 for Jan 1 coverage |
| Covered California | Nov 1 to Jan 31 | Longest common window |
| Get Covered New Jersey | Nov 1 to Jan 31 | Same window as California |
| HealthSource RI (Rhode Island) | Nov 1, 2026 to Jan 31, 2027 | New state subsidy starts Jan 2027 |
| Massachusetts Health Connector | Oct 23, 2026 to Jan 23, 2027 | Starts earlier than any other window |
| Your Health Idaho | Oct 15 to Dec 15 | Opens first, closes first |
Idaho is the one to watch. Your Health Idaho’s enrollment page states open enrollment is “October 15 to December 15 each year,” which means Idahoans are done shopping a full month before residents of most other states have hit their January 1 deadline.
Massachusetts moved earlier too. The Health Connector’s renewal page says the 2027 open enrollment period is October 23, 2026 through January 23, 2027, and flags that this is earlier than in past years.
Rhode Island is worth a second look for a different reason. HealthSource RI is launching the Rhode Island Marketplace Affordability Program in January 2027, state money layered on top of federal tax credits, aimed at households under 200% of the federal poverty level and at some households over 400%. It exists because the enhanced federal credits expired. If you live in a state-based marketplace, check whether your state built something similar before you assume the federal numbers are your numbers.
If your state is not listed above, confirm your window on your own marketplace’s site rather than a national roundup. The commercial comparison charts circulating this fall contradict each other on several states.
Job-Based Open Enrollment Is Whatever Your Employer Says
If you get coverage through work, none of the above applies to you. HealthCare.gov states it directly: job-based plans may have different open enrollment periods, and you should check with your employer.
Employer windows are typically two to four weeks somewhere between late September and early December, set by the employer’s plan year and benefits administrator. Most close well before HealthCare.gov’s December 15 date. Some employers require active re-election every year, meaning you lose coverage if you do nothing, while others auto-renew you into last year’s plan.
That is the moment to reread your plan documents rather than clicking “same as last year.” Deductibles and out-of-pocket maximums reset and often rise. If you are choosing between plan types, our guides to HMO vs. PPO plans, health insurance deductibles and the out-of-pocket maximum cover what the numbers on the comparison grid actually mean.
Medicare Has Its Own Calendar
Medicare’s dates are not the Marketplace’s dates, and confusing the two is the single most common mistake in this whole topic.
- Medicare Open Enrollment: October 15 to December 7. Medicare.gov describes this as the time each year you can join, drop or switch a Medicare Advantage plan or a Medicare drug plan, or move between Original Medicare and Medicare Advantage. Changes take effect January 1, and the plan must receive your request by December 7.
- Medicare Advantage Open Enrollment: January 1 to March 31. Only if you are already in a Medicare Advantage plan. You can switch to a different Medicare Advantage plan or drop back to Original Medicare and pick up a drug plan. Coverage starts the first of the month after the plan gets your request. If you are turning 65, your Initial Enrollment Period is a personal window rather than an annual calendar date. Medicare.gov describes it as starting three months before you get Medicare and ending three months after.
If You Missed It
Missing open enrollment is not automatically a lost year. A qualifying life event opens a special enrollment period, usually 60 days long. Losing job-based coverage, moving, getting married, having a baby and aging off a parent’s plan all count.
That last one has its own timeline. Our guide to staying on a parent’s health insurance until 26 covers what happens on your birthday and what window opens after.
If you are between jobs, compare the marketplace against COBRA before you default to continuation coverage. The math is often lopsided, and we walk through it in health insurance for the unemployed and COBRA insurance cost.
And if you are genuinely locked out until next November, plan for the gap rather than hoping. Free and sliding-scale clinics price visits against your income, and our uninsured start-here guide covers what to do about prescriptions, urgent care and hospital bills in the meantime.
The Bottom Line
Write down two dates: December 15, 2026 if you want coverage on January 1, and January 15, 2027 as the outer limit on HealthCare.gov. If you live in California, New Jersey, Rhode Island, Massachusetts or Idaho, use your state’s window instead, and check your own marketplace’s site rather than a national chart.
Then check what the plan will actually cost you before you pick one. The enhanced premium tax credits that made 2021 through 2025 unusually cheap are gone, which changes the arithmetic for nearly everyone shopping this fall. We cover what expired and what replaced it in ACA subsidy expiration, the qualifying income bands in ACA subsidy income limits, and how the credit gets paid to your insurer in advance premium tax credit.