What Is Open Enrollment and When Is It?

Your plan can change its premium, provider network and drug list every Jan. 1, and it renews automatically if you do nothing. Medicare Advantage and Part D plans mail an Annual Notice of Change in September with every change for the next year. ACA Marketplace insurers send a renewal notice before open enrollment begins.

ACA enrollment on HealthCare.gov stays open through Jan. 15, 2027, but Medicare closes Dec. 7, 2026. For households with someone approaching 65 or transitioning off employer coverage, both windows apply at the same time with different deadlines. I’d set a calendar reminder each September to review both before either window opens.

Open enrollment is the yearly window when you can sign up for, renew or change your health insurance plan. In states that use HealthCare.gov, the ACA Marketplace open enrollment period accepts applications from Nov. 1 to Jan. 15 each year. Outside this window, you can't enroll in or switch Marketplace coverage without a qualifying life event.

A qualifying life event is any change in your circumstances that temporarily reopens your enrollment window. Job loss, marriage and the birth of a child all qualify. Medicare and employer-sponsored plans follow their own schedules with different deadlines from the ACA window.

Medicare’s window closes Dec. 7. The ACA window on HealthCare.gov closes Jan. 15. Both apply at the same time to anyone approaching 65 or transitioning off employer coverage.

Part B, the part of Medicare that covers doctor visits and outpatient care, has its own enrollment schedule. If you didn’t sign up when you turned 65, you can enroll from Jan. 1 to March 31, and coverage begins the month after you sign up. Each 12-month period you could have had Part B and didn’t adds 10% to your premium for as long as you have it. Coverage through your own or your spouse’s current job lets you delay without that penalty.

Review your current plan before you compare new ones. Coverage details, network providers and drug lists can all change at renewal. Medicare Advantage and Part D plans mail an Annual Notice of Change in September, and ACA Marketplace insurers send a renewal notice before open enrollment. Either notice shows what changes before you’re locked in for the year.

• Enroll in a New Plan Sign up for health coverage for the first time through the Marketplace, Medicare Advantage or your employer's group health plan.   
• Renew Your Current Plan Keep your existing ACA Marketplace, Medicare or employer plan for the next coverage year. Your plan sends a notice before open enrollment with its 2027 premiums and benefits. For Medicare Advantage and Part D plans, that notice is the Annual Notice of Change.
• Switch Plans or Metal Tiers Change to a different health plan, insurer or metal tier. The four tiers, Bronze, Silver, Gold and Platinum, set how costs split between you and the insurer.
• Bronze plans have the lowest premiums of the four tiers, and you pay a bigger share of each bill when you use care. The 2027 out-of-pocket maximum, the most you pay in a plan year before your insurer covers 100%, is $12,000 for individual coverage.
• Add or Remove Dependents Update your plan to include or drop a spouse, child or other household member. Adding dependents increases your monthly premium, though children may qualify for CHIP at lower cost.   
• Drop Coverage Cancel your plan entirely. You won’t have health insurance until the next open enrollment period or a qualifying life event. Four states (California, Massachusetts, New Jersey, Rhode Island) and Washington, D.C., charge penalties for going uninsured. Vermont requires residents to have coverage but charges no penalty.

Your next step depends on why you missed it and which plan type you were enrolling in. A missed ACA open enrollment leaves more options than a missed Medicare window. 

Check HealthCare.gov first: Medicaid and CHIP accept applications year-round, and a qualifying life event in the past 60 days opens a special enrollment period. For Medicare, there's no comparable path back once the deadline passes.

You can enroll in or change health insurance outside of open enrollment through a special enrollment period. HealthCare.gov gives Marketplace applicants 60 days before or after a qualifying life event to select a new plan.   

Employer-sponsored plans must offer at least 30 days for enrollment after a qualifying event, per the U.S. Department of Labor. Medicaid and CHIP accept applications year-round regardless of life events.

Most health-related insurance plans restrict enrollment to a fixed annual window. ACA Marketplace plans, Medicare Advantage, Medicare Part D and employer group health plans all require enrollment during their designated open enrollment period. You can't sign up for or switch these plans outside their enrollment windows unless you qualify for a special enrollment period.

Medigap, also called Medicare Supplement insurance, follows different rules from every other plan. You get one guaranteed-issue window: the six months after you turn 65 and enroll in Medicare Part B.

Guaranteed issue means an insurer can't deny you coverage or charge more because of a health condition. After those six months, it can.

Several insurance types allow enrollment at any time without waiting for an annual open enrollment window. Medicaid, CHIP and individual dental and vision plans all follow different rules from ACA Marketplace and Medicare coverage.   

• Medicaid and CHIP Apply any time, year-round, at HealthCare.gov or through your state's Medicaid agency. Eligibility is based on household income and family size.
• Individual Dental and Vision Plans Dental and vision plans sold outside the Marketplace are available year-round with no enrollment restrictions.

Medicaid covers adults with household income below 138% of the federal poverty level in states that expanded Medicaid, which covers most states. Eligibility also depends on household size. Apply at HealthCare.gov. Coverage can start immediately if you qualify.

Your plan’s renewal notice lists every update for the coming year. For Medicare Advantage and Part D plans, the notice is called the Annual Notice of Change. Read it to catch premium increases, network shifts and drug removals before you lock in.

Four mistakes consistently cost people money after coverage starts, with no way to correct them until next year.

These answers cover how enrollment windows work, what qualifies for special enrollment and what happens if you miss a deadline.