KFF Brief Breaks Down What Medicare Open Enrollment Covers This Fall

Medicare's annual Open Enrollment Period runs from October 15 to December 7, 2026, giving beneficiaries just under eight weeks to review and change their coverage for the year ahead, according to a brief published October 9, 2026 by KFF, the health policy research organization formerly known as the Kaiser Family Foundation. The brief answers common questions about what beneficiaries can and cannot change during this window, and it arrives as millions of people weigh whether to stay in their current Medicare Advantage or Part D plan or switch to a new one for 2027.

For readers of Medicare Plan Path, the timing matters more than the announcement itself. Any plan change made during this period takes effect January 1, 2027, and the December 7 deadline is firm: requests submitted after that date generally will not be processed for the coming plan year.

What Changes Are Allowed During Open Enrollment

According to KFF's brief, the fall Open Enrollment Period is the main window for beneficiaries to move between the two basic ways of getting Medicare coverage: Original Medicare (Parts A and B) and Medicare Advantage (Part C), the private plan alternative that bundles hospital, medical and often drug coverage into one plan. Within that window, beneficiaries can also switch from one Medicare Advantage plan to another, switch from one standalone Part D prescription drug plan to another, join a Part D plan for the first time if they have Original Medicare without drug coverage, or drop Part D coverage entirely.

The brief distinguishes this period from the separate Medicare Advantage Open Enrollment Period that runs January 1 through March 31 each year, which allows a narrower set of changes, such as switching Medicare Advantage plans once or returning to Original Medicare, but does not allow joining a standalone Part D plan from scratch. Mixing up these two windows is one of the more common sources of confusion that KFF's question and answer format is designed to address.

Key Takeaway

The 2026 fall Open Enrollment Period closes December 7, 2026, and any coverage change made before then takes effect January 1, 2027. Medigap, also called Medicare Supplement coverage, is not governed by this window and generally requires medical underwriting outside specific guaranteed issue situations.

Why This Year's Plan Review Carries More Weight

This section reflects analysis from Medicare Plan Path, not a finding in the KFF brief: the practical stakes of open enrollment have grown because Medicare Advantage and Part D plan details rarely stay the same from one year to the next. Insurers routinely adjust premiums, drug formularies, provider networks and out of pocket maximums each January, so a plan that fit a beneficiary's budget and medication list in 2026 may look different in 2027. KFF's brief does not report specific premium or benefit figures for 2027, so beneficiaries should check their own plan's Annual Notice of Change letter, which insurers are required to mail each fall, rather than assume last year's costs will carry forward.

The brief's question and answer structure also signals that even a long standing benefit like Medicare's open enrollment window remains a source of confusion for many beneficiaries, including who is eligible, what can and cannot be changed, and how the fall window differs from the Medicare Advantage only window that runs each January through March. That confusion carries real cost: missing the December 7 deadline can mean staying in a plan whose network or drug list no longer fits, for a full calendar year.

Steps to Take Before December 7, 2026

Readers weighing a change should start with a few concrete checks rather than a general comparison. First, confirm whether current prescriptions remain on next year's formulary, the list of drugs a Part D or Medicare Advantage plan covers, since formularies can change annually even within the same plan. Second, verify that preferred doctors, specialists and hospitals remain in network for 2027, particularly for Medicare Advantage plans, which rely on defined provider networks more than Original Medicare does. Third, compare total expected costs, not just premiums, including deductibles, copays and out of pocket maximums, using Medicare's official Plan Finder tool at medicare.gov or by working with a licensed insurance agent who can walk through plan specific numbers.

Beneficiaries who are satisfied with their current coverage do not need to take any action; plans continue automatically into 2027 unless a Medicare Advantage or Part D plan is discontinued by the insurer, in which case the plan sends a separate non renewal notice. Given how much plan details can shift from year to year, Medicare Plan Path recommends against assuming no action is always the right call. A brief annual comparison, even for beneficiaries who end up keeping their current plan, is the only way to confirm that the plan that fit 2026 still fits 2027. For the full set of questions KFF addresses about eligibility, timing and coverage options, see the original brief.