Important Deadlines
When Is Open Enrollment for Health Insurance and Medicare?
ACA Open Enrollment for 2027 coverage opens November 1, 2026, and December 15, 2026 is the practical target for coverage starting January 1. Medicare AEP runs October 15 through December 7, 2026. Final ACA end dates differ by Marketplace, so confirm yours.
What Are the Key Enrollment Periods for 2026-2027?
ACA Open Enrollment (2027 Plan Year)
Starts November 1, 2026
The annual window to enroll in or change ACA Marketplace plans for 2027 coverage opens November 1, 2026. December 15, 2026 is the practical target for January 1, 2027 coverage in most states. The final end date differs between the federal Marketplace and state-run Marketplaces, so confirm yours before you rely on it.
Who: Anyone buying individual or family health insurance.
Medicare Initial Enrollment Period
3 months before, 3 months after your 65th birthday
Your 7-month window to enroll in Medicare Parts A, B, and D. Missing this can result in permanent late enrollment penalties of 10% per year for Part B.
Who: People turning 65 who aren't automatically enrolled.
Medicare Annual Election Period (AEP) 2026
October 15, 2026, December 7, 2026
Switch Medicare Advantage plans, return to Original Medicare, or change Part D drug plans for the 2027 plan year. Changes take effect January 1, 2027.
Who: Current Medicare beneficiaries who want to change their plan.
Medicare Advantage Open Enrollment
January 1 through March 31, 2027
If you have Medicare Advantage, switch to a different Advantage plan or return to Original Medicare + Part D. One change allowed.
Who: Current Medicare Advantage enrollees only.
Medigap Open Enrollment
6 months starting when you're 65+ AND enrolled in Part B
Your ONE-TIME guaranteed-issue window for Medicare Supplement plans. Insurers cannot deny you or charge more based on health. Miss it and you may face medical underwriting for life.
Who: People newly eligible for Medicare who want a Supplement plan.
Medicare Part D Initial Enrollment
Same as your Medicare Initial Enrollment Period
First chance to enroll in a Part D prescription drug plan. Each month without creditable coverage adds a 1% permanent penalty to your premium.
Who: Anyone enrolling in Medicare for the first time.
What Qualifies for a Special Enrollment Period?
You can enroll in ACA coverage outside Open Enrollment with a qualifying life event. You typically have 60 days from the event. According to CMS, Special Enrollment accounts for 40% of all marketplace enrollments.
What Are the Penalties for Missing Enrollment?
Medicare Part B Late Enrollment Penalty
10% of the standard premium ($202.90/month in 2026) for every 12-month period you could have had Part B but didn't. This penalty is permanent, you pay it every month for the rest of your life.
Medicare Part D Late Enrollment Penalty
1% of the national base beneficiary premium ($34.70 in 2026) per month without creditable drug coverage. Also permanent. Example: 24 months late = $8.33/month added to your Part D premium forever.
Medigap Underwriting After Open Enrollment
If you miss your 6-month Medigap Open Enrollment window, insurance companies can use medical underwriting, meaning they can charge more, add exclusions, or deny coverage entirely based on health conditions.
Renewal Checklist for the 2027 Plan Year
Read your renewal notice rather than assuming it settles anything. Confirm your eligibility, that the plan is still available to you, the premium payment required, and the coverage effective date. Work through this before your Marketplace deadline.
- Review the renewal notice and confirm eligibility, plan availability, the premium payment required, and the effective date.
- Update the income you expect for 2027, including self-employment profit and a spouse's wages.
- Confirm household size and who needs coverage for which months.
- Compare the new net premium after any credit against the other plans priced in your area, not just last year's plan.
- Check the exact doctors and facilities you use against the plan's current network, by name and location.
- Check each prescription: dose, formulary tier, prior authorization, step therapy, and which pharmacies are covered.
- Compare the deductible, copays, and out-of-pocket maximum, then total the expected annual cost, not only the premium.
- Note the required first premium payment and the exact coverage effective date.
- Note any employer coverage offered to anyone in the household, and the employer's own enrollment dates.
- Confirm the final deadline for your Marketplace, then decide how much credit to take in advance.
Source: HealthCare.gov, keep or change your plan. Note: HealthCare.gov consumer guidance and the 2025 CMS rule currently differ on closing-date information, so check your own Marketplace for the date that applies to you. The November 1 start and the December 15 target for January 1 coverage are unchanged.
Frequently Asked Questions About Enrollment Dates
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