A Medicare Advantage member whose hospital leaves the plan’s network may hold a second way out of the plan, and it is not the exit most members use. Medicare’s own guide to Medigap lists a network that “has a significant change” among four situations that carry a guaranteed right to buy a Medigap policy. The right is printed in the guide. Whether a particular hospital departure sets it off depends on a phrase that the guide never defines.
Two parts of The 2027 Medicare Open Enrollment Decision Kit fit this network question: the Medigap guaranteed-issue rights section with its call script, and the Open Enrollment calendar.
Open the Medigap call script and the Open Enrollment calendar →
Where a hospital’s exit fits in the guide’s list of four
The list sits in the March 2026 edition of Medicare’s guide to Medigap health insurance, CMS Product No. 02110. A person with a Medicare Advantage plan has the guaranteed right when the plan is leaving Medicare, when it stops giving care in the person’s area, when the person moves out of the plan’s service area, or when the plan’s network has a significant change. Three of the four describe a plan that ends or a member who leaves. The fourth is the only one that can apply while the plan carries on and the member stays in the same house, which makes it the one that matters when a hospital walks away from a contract.
The guide defines a guaranteed issue right as a situation in which insurance companies are required by law to sell a Medigap policy. In these situations the policies on offer are Medigap Plans A, B, C, D, F and G sold by an insurance company in the member’s state, with footnoted limits on some of the letters. The insurer cannot use medical underwriting, and it cannot charge more because of past or present health problems. For a member with a long-running condition, the bar on health screening is what gives the right its weight.
The 63-day clock and the rule that Medigap cannot start early
Timing is spelled out more precisely than the trigger. The guide allows an application as early as 60 days before the Medicare Advantage coverage ends, when the member is choosing to leave the plan, or by the date in the plan’s termination notice, with the final deadline falling 63 days past the end of that coverage. One more condition applies: the Medicare Advantage coverage has to finish before any Medigap policy can begin.
Those two sentences set up a sequence. The Medigap application can go in ahead of time, but the policy begins only once the Medicare Advantage plan is gone, so leaving the plan is a separate act that has to happen through whichever enrollment period applies. Minnesota’s Aging Pathways Medicare Open Enrollment page, updated September 17, 2026, lists the annual Open Enrollment period as October 15 through December 7. The same guide shows the 63-day figure is not unique to network changes: a person who joined Medicare Advantage within the first year of Medicare eligibility at 65 and decides within that first year to return to Original Medicare gets a trial right with the same 60-day and 63-day span.
Who decides that a network change is significant
The Medigap guide does not define the term. The clearest answer on record comes from a different CMS document, a December 2024 set of answers to questions from state insurance regulators. It says CMS “has a rigorous internal review process that evaluates the totality of the unique circumstances around each termination.” If CMS determines that a provider termination is a significant change in a plan’s network, it communicates that finding to the plan, and the plan is then required to notify affected enrollees that they have a special enrollment period.
The same document describes the evidence trail. When a member disenrolls from the Medicare Advantage plan, the plan sends a notification letter, and the document says the beneficiary can provide that letter to the Medigap plan as evidence of the right to enroll. Under the CMS answers, then, the significance finding belongs to CMS, the letter belongs to the plan, and the member’s job is to carry the letter to the Medigap insurer. A hospital’s exit is one kind of provider termination, and whether any given exit counts is the case-by-case determination CMS describes.
What a finished determination looks like in Nevada
A notice posted by the Nevada Division of Insurance about Prominence Healthfirst shows the finished product. It states that CMS determined the plan’s provider network change was significant. It names the federal Medigap guaranteed-issue right to buy Plans A, B, C, D, G and F, with age-based limits, and it gives the same span of 60 days before the Medicare Advantage coverage ends to 63 days after. It also lays out the special enrollment period mechanics: the period begins the month enrollees are notified of their eligibility and ends two calendar months after that month, and it can be used once per significant network change.
Two points follow from the notice. A determination attaches to a specific network change by a specific plan, not to hospital departures in general. And the 63-day span matches the Medigap guide, so the number does not change from one company to the next.
Fairview’s January 1 change, still waiting for a label
A live example of a provider leaving a Medicare Advantage insurer’s network appears on M Health Fairview’s Medicare Open Enrollment page. It says Fairview will no longer schedule patients with UnitedHealthcare Medicare Advantage plans beginning January 1, 2027. Nothing in the sources read for this piece says that CMS has made a significance determination about that change, or that UnitedHealthcare has sent a letter tying it to the Medigap right. The page is an Open Enrollment notice from the provider’s side, and it is cited here for the facts it states, not as proof that the right attaches to it.
A right that rests on an undefined word and a letter that may not exist yet
The difficulty lies in the gap between the two CMS documents. The Medigap guide states the right in the member’s favor and leaves “significant” undefined. The CMS answers keep the finding for the agency and route the proof through a plan letter. A member whose hospital has left therefore has to establish three things in order: that CMS treated the termination as significant, that the plan has issued the letter, and that the 63-day clock has not run out. The sources read for this piece do not say what a Medigap insurer must accept from a member who asserts the right without a letter, and they do not say how long a plan has to send one.
Asserting the right is a request, not a purchase. The guide attaches no charge to it, and during guaranteed issue the insurer cannot charge more for health problems; the premium of a policy, if one is bought, is a separate matter. Nothing about the request requires paid help.
The official route is the same for every member. The Medigap guide points to 1-800-MEDICARE, 1-800-633-4227, and to shiphelp.org for the number of the State Health Insurance Assistance Program, and the national SHIP site describes its services as one-on-one counseling from a trusted, unbiased source, with a phone line at 877-839-2675.
A hospital contract can end before the proof of a Medigap right arrives
The Medigap guaranteed-issue right for a significant network change runs on a 63-day clock, yet the plan letter that serves as evidence may not exist when a hospital leaves. That gap between the exit date and the paperwork is the costly and confusing part of the news, and it falls on the member who has to apply on time.
The 2027 Medicare Open Enrollment Decision Kit includes the Medigap guaranteed-issue rights section with a call script and the Open Enrollment calendar, so the calls to the insurer and the dates for leaving the plan can be laid out side by side.
Get The 2027 Medicare Open Enrollment Decision Kit before a hospital exit starts the 63-day clock →
This piece was drafted with AI assistance; the rules and dates were checked against Medicare’s Medigap guide, CMS’s answers to state regulators and the Nevada Division of Insurance notice.
