Medicare Enrollment Period Finder
Enter a date of birth and a situation; get every window they qualify for, with exact deadlines and coverage start dates — and, for the ones they don't qualify for, the specific reason why.
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Enter a date of birth to see every window they qualify for.
Estimate only, based on CY2026 figures (CMS enrollment period rules). This is not an official determination. MedicareCopilot is not affiliated with or endorsed by CMS, Medicare, the Social Security Administration, or any government agency — official amounts and eligibility determinations are made by SSA and CMS. Special Enrollment Period rules change annually — the dual and Extra Help windows were restructured on 1 January 2025. This tool provides general information only and is not medical, legal, or tax advice. Figures last verified 2026-07-27.
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The Medicare enrollment periods
The Initial Enrollment Period is 7 months long: the 3 months before the month you turn 65, that month, and the 3 months after. If you were born on the first of a month, Medicare treats you as turning 65 in the previous month, so the whole window shifts back one month.
The General Enrollment Period runs January 1 through March 31 each year for anyone who missed their Initial Enrollment Period. Coverage now begins the first of the month after you sign up. Before 2023 it did not start until July 1, and a great deal of published material still says so.
The Annual Enrollment Period runs October 15 through December 7 and is the main opportunity to join, switch, or drop a Medicare Advantage or Part D plan. Coverage always starts January 1.
The Medicare Advantage Open Enrollment Period runs January 1 through March 31, but only for people already enrolled in a Medicare Advantage plan, and allows one change.
A Part B Special Enrollment Period of 8 months opens when group health coverage from active employment ends, at an employer with 20 or more employees. COBRA, retiree coverage, and severance benefits do not qualify — the clock runs from the end of the job, not the end of COBRA.
Medigap Open Enrollment is the one that never reopens. It lasts 6 months from the first month you are both 65 and enrolled in Part B, and it is the only time you can buy any Medigap policy with no medical underwriting.
Common questions
When is the Medicare Initial Enrollment Period?
The Initial Enrollment Period is 7 months long: the 3 months before the month you turn 65, the month you turn 65, and the 3 months after.
If you were born on the first day of a month, Medicare treats you as turning 65 in the previous month, so the entire window shifts back by one month.
When is the Medicare General Enrollment Period?
The General Enrollment Period runs January 1 through March 31 every year, for people who missed their Initial Enrollment Period and do not qualify for a Special Enrollment Period.
Coverage begins the first of the month after you sign up. Before 2023 coverage did not begin until July 1 regardless of when you enrolled, and a lot of published material still describes that older rule.
When is the Medicare Annual Enrollment Period?
The Annual Enrollment Period runs October 15 through December 7 each year. It is the main opportunity to join, switch, or drop a Medicare Advantage or Part D plan.
Coverage from a change made during AEP always begins on January 1 of the following year.
Can I change Medicare Advantage plans in January?
Yes, but only if you are already enrolled in a Medicare Advantage plan on January 1. The Medicare Advantage Open Enrollment Period runs January 1 through March 31 and allows one change.
It cannot be used to move from Original Medicare into a Medicare Advantage plan, and coverage starts the first of the month after the change.
Does COBRA extend my Medicare Part B enrollment window?
No. The 8-month Part B Special Enrollment Period runs from the end of active employment or the end of the group health plan, whichever comes first — not from the end of COBRA.
COBRA, retiree coverage, and severance health benefits do not qualify for the Part B Special Enrollment Period. Waiting for COBRA to run out before enrolling in Part B is one of the most common and most expensive Medicare mistakes.
Did the enrollment rules for people with Medicaid or Extra Help change?
Yes, on 1 January 2025. The quarterly Special Enrollment Period that let dual-eligible and Extra Help beneficiaries change Medicare Advantage plans four times a year was eliminated.
It was replaced by a monthly Special Enrollment Period that applies to standalone Part D plans and cannot be used to join a Medicare Advantage plan, plus a separate monthly integrated-care window for full-benefit duals moving into an aligned D-SNP. Partial-benefit duals and Extra Help-only beneficiaries lost the ability to change Medicare Advantage plans outside AEP and OEP.
When can I buy a Medigap policy without medical underwriting?
During your Medigap Open Enrollment Period: 6 months beginning the first month you are both 65 or older and enrolled in Part B. During it, insurers must sell you any Medigap policy they offer, at the standard rate, regardless of health history.
This window does not reopen. Once it closes, most Medigap applications are subject to medical underwriting and can be declined, though several states extend guaranteed-issue rights beyond the federal rule.
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