Important Deadlines
When Is Open Enrollment for Health Insurance and Medicare?
ACA Open Enrollment runs November 1, January 15. Medicare AEP runs October 15, December 7. Missing a deadline can mean permanent penalties or a full year without coverage.
What Are the Key Enrollment Periods for 2026?
ACA Open Enrollment
November 1, 2025, January 15, 2026
The annual window to enroll in or change ACA marketplace plans. Enroll by December 15 for January 1 coverage. Over 21 million Americans enrolled through the marketplace in 2025 (CMS).
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
October 15, December 7 (every year)
Switch Medicare Advantage plans, return to Original Medicare, or change Part D drug plans. Changes take effect January 1.
Who: Current Medicare beneficiaries who want to change their plan.
Medicare Advantage Open Enrollment
January 1, March 31 (every year)
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.
Frequently Asked Questions About Enrollment Dates
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