Can You Change Medicare Supplement Plans During Open Enrollment? 2027 Rules

Reviewed by Russell Noga, Licensed Medicare Insurance Broker (all 50 states) — Last updated November 5, 2026

Every October the mailbox fills with Medicare ads, and many people with a Medicare Supplement policy assume the fall season is their once-a-year chance to trade it in. It isn’t. Federal law has no yearly Medigap enrollment period, and the dates on the television commercials belong to other parts of Medicare.

That cuts both ways. Nothing stops you from shopping for a different Medigap policy this month, and nothing about December 7 closes the door. What the calendar does control is your drug plan, any move out of Medicare Advantage and, in three states, a new Medigap right built around these exact dates.

Medicare uses the phrase open enrollment for several unrelated windows, which is the root of the confusion. The one running now, October 15 through December 7, 2026, is the Annual Enrollment Period. Changes made in it take effect January 1, 2027, and it applies to Medicare Advantage and Part D drug plans.

The Medicare Advantage Open Enrollment Period, January 1 through March 31, is narrower still: only people already in a Medicare Advantage plan can use it, for one change. Your Medigap open enrollment is a different thing entirely, a single 6-month stretch that begins the month you are 65 or older and enrolled in Part B. It never repeats. Our main guide to Medicare Supplement open enrollment covers how that first window is counted.

Line the windows up against the kinds of changes people ask about and the pattern is clear: the fall dates move drug and Medicare Advantage coverage, while Medigap runs on its own rules.

Sources: CMS enrollment period rules; Medicare.gov Medigap switching guidance; state insurance department rules summarized by KFF (October 13, 2026).

Since there is no seasonal gate, you can apply for a new policy whenever a lower price or a different plan letter appeals to you. The catch is the application itself. Outside protected windows, most insurers ask about recent diagnoses, hospital stays, prescriptions and planned surgeries, and they can decline you or place you in a higher rate class. The typical question set is laid out in Medigap underwriting questions.

Plan direction matters too. Moving to a plan with fewer benefits tends to be easier to approve than moving up. Common examples are covered in switching from Plan F to Plan G and the reverse-direction problem in switching from Plan N to Plan G.

Medigap policies sold since January 1, 2006 can’t include prescription drug coverage, so almost every Medigap holder who has drug coverage gets it from a separate Part D plan. That plan is the piece the Annual Enrollment Period is built for. Premiums, formularies and pharmacy networks reset every January, and the window closing December 7 is the routine time to compare them.

For 2027, CMS set the standard Part D deductible at up to $700, up from $615, and the yearly out-of-pocket cap at $2,400, up from $2,100. Anyone on costly medicines should check how their current plan treats each drug in 2027 before the window closes. Plan options are explained in Medicare Part D, with 2027 premium and cap details in Medicare Part D cost.

The fall window, and the January to March window for current members, let you leave a Medicare Advantage plan and return to Original Medicare. Medicare will accept that move. A Medigap insurer doesn’t have to, unless you hold a guaranteed issue right or live in a state that grants one.

The main federal protection is the Medigap trial right, which covers people in their first 12 months of Medicare Advantage under specific conditions. Past that year, most applicants returning from Medicare Advantage go through underwriting. The order of steps matters: apply for the Medigap policy and get an approval before your Medicare Advantage disenrollment takes effect, so a decline doesn’t leave you on Original Medicare with no supplement.

Thinking about the opposite direction this fall? Read switching from a Medicare Supplement to Medicare Advantage first, since giving up a Medigap policy can be hard to undo.

A handful of states now borrow Medicare’s own calendar for Medigap, which makes the answer to the headline question yes for some residents. Each one works differently:

Most state switching rules have nothing to do with the fall season. KFF’s October 13, 2026 review counts 16 birthday-rule states, where current policyholders get a window tied to their own birthday: California, Delaware, Idaho, Illinois, Indiana, Kentucky, Louisiana, Maryland, Nevada, New Mexico, Oklahoma, Oregon, Utah, Virginia, West Virginia and Wyoming. Missouri keys its window to the policy anniversary instead, and Connecticut and New York keep guaranteed issue open all year.

Maine and Washington let policyholders move to equal or lesser benefits at any time if their coverage hasn’t lapsed more than 90 days, with Washington limiting Plan A holders to another Plan A. The details of the 45-day Illinois version are in the Illinois Medicare Supplement birthday rule guide, the original model is in the California Medicare Supplement birthday rule guide, and every state’s window length sits in Medicare Supplement guaranteed issue rights by state.

Many people like a new policy to start with the new year, alongside a new drug plan. The sequence below keeps you covered the whole way, whether or not your state gives you a protected window.

Returning a new policy during the free look only works out if the old one is still active, as the Medicare Supplement free look period guide explains.

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