Joining Medicare Advantage is easy. Leaving is not.

Part 1

The two doors are not the same width

Every autumn the choice arrives as a pair of doors. Behind one is Original Medicare, run by the federal government, with a private Medicare Supplement Insurance policy, usually called Medigap, sold alongside it to cover the share Medicare leaves behind. Behind the other is Medicare Advantage, a private plan paid by the government to deliver the same benefits, usually with drug coverage folded in and a list of extras attached.

Both doors are open. Anyone with Part A and Part B who lives in a plan's service area can join a Medicare Advantage plan, in any year, with any pre-existing condition. Anyone already in a Medicare Advantage plan can return to Original Medicare in the right window.

Coming back, the doors are not the same width. Returning to Original Medicare is straightforward. Returning to Original Medicare and buying the Medigap policy that caps what Original Medicare leaves open is a separate question with a separate answer, because for most people the right to buy that policy lasted six months and then expired.

How the country has split

Neither door is the unusual choice. In calendar year 2025, average monthly enrollment ran 34.9 million people in Medicare Advantage against 34.0 million in Original Medicare. The remainder of the 69.4 million people holding Part A, Part B or both sat in other kinds of health plan. The country is split close to evenly, and the split has been moving toward Advantage for years.

What this guide covers

What each door costs in 2026, in the actual published amounts. What the Advantage plan's yearly spending limit counts and, more usefully, what it does not. The six month window that decides whether a Medigap policy can be bought at all. The two trial rights that are the only clean way back once that window has closed. And the two enrollment periods each year, with the exact list of what each one is allowed to change.

This guide is educational information. It is not legal, tax or financial advice.

Part 2

What Original Medicare costs in 2026

Original Medicare is two parts with two different billing habits. Part A covers inpatient hospital care, skilled nursing facility care, hospice and some home health care, and it charges by the stay. Part B covers doctors, outpatient care, tests, equipment and most preventive services, and it charges by the year and then by the visit.

Part A charges by the benefit period, not by the year

Part A costs no premium at all for anyone who paid Medicare taxes long enough to qualify, which is most people reaching 65. Anyone who did not buys in: $311 a month with at least 30 quarters of coverage, or married to someone who has them, and $565 a month with fewer.

What Part A charges instead is a deductible of $1,736 in 2026, and that deductible is per benefit period rather than per year. A benefit period ends after 60 days in a row with no inpatient or skilled nursing care. Medicare's own handbook is blunt about the consequence: a new benefit period means paying the deductible again, and that can happen more than once in a single calendar year.

Part B charges a premium, a deductible and then a percentage

The standard Part B premium in 2026 is $202.90 a month, up $17.90 from $185.00 in 2025. Higher incomes pay more, on a scale read from a tax return filed two years earlier, rising to $689.90 a month at $500,000 or more filing alone and $750,000 or more filing jointly.

After the premium comes an annual deductible of $283. After the deductible, Part B pays its share and the patient pays 20 percent of the Medicare-approved amount for most services.

The sentence the whole choice turns on

That 20 percent has no ceiling. The Medicare handbook states it in one line: there is no yearly limit on what a person pays out of pocket under Original Medicare unless they hold supplemental coverage such as Medigap, Medicaid, or employer, retiree or union coverage.

Twenty percent of an ordinary year is a small number. Twenty percent of a cardiac surgery, a course of chemotherapy or a long run of outpatient infusions is not, and nothing inside the program stops it climbing. Original Medicare on its own is excellent coverage with an open-ended tail.

Part 3

What a Medicare Advantage plan costs in 2026

A Medicare Advantage plan replaces the way Original Medicare pays, not the fact of being enrolled in it. The Part B premium of $202.90 a month is still owed, to Medicare, every month, on top of whatever the plan charges. Some plans charge a premium of their own. Some charge nothing. A few pay back part or all of the Part B premium, which the industry calls a Part B premium reduction.

In place of the 20 percent coinsurance, plans generally charge fixed copayments per visit or per service, and they may run their own deductibles. Federal rules cap how far this can go in a few places: a plan cannot charge more than Original Medicare would for chemotherapy, dialysis, or skilled nursing facility days 21 through 100.

The yearly limit, and how high it is allowed to be

The structural difference is the one Original Medicare does not offer. Every Medicare Advantage plan has to cap what a member pays in a year for covered Medicare services. Once that cap is reached, the plan pays everything for the rest of the year.

How high the cap sits is the plan's choice inside federal bands. CMS publishes three of them each year, and the ceiling actually fell slightly for 2026, from $9,350 to $9,250.

A plan sitting in the lower band buys itself looser rules on cost sharing elsewhere. A plan sitting at the mandatory ceiling can ask a member for $9,250 in a bad year before the cap engages, which is why two plans with identical $0 premiums are not the same product.

The second limit that only appears on plans with out-of-network coverage

Plans that pay something toward care outside the network, typically the PPO designs, carry a second and higher cap that counts in-network and out-of-network spending together. For 2026 that combined limit runs as high as $13,900 for a plan whose in-network limit sits in the mandatory band.

Both numbers appear in the plan documents. Reading only the first one understates the exposure of a plan that is being chosen precisely because it covers care outside its network.

Part 4

The yearly limit and the bills it does not count

The yearly limit is real protection and it is narrower than it sounds. Medicare defines it against one specific thing: a plan's yearly limit on out-of-pocket costs for all Part A and Part B covered services. Everything that is not a Part A or Part B covered service sits outside the cap.

Three categories that do not count toward it

Prescription drugs. Drug coverage is Part D, not Part A or Part B, and it runs its own separate cap. In 2026 that is a maximum deductible of $615 and an out-of-pocket ceiling of $2,100. The $2,100 is genuine protection, and it stacks on top of the medical limit rather than sitting inside it.

The extras. Dental, vision, hearing, fitness and transportation benefits are the reason many plans are chosen. Medicare defines the yearly limit over Part A and Part B services, and these are not Part A or Part B services, because Original Medicare does not cover them. That last step is a conclusion drawn from how the limit is defined rather than a separately published rule, so the place to confirm it for any one plan is that plan's Evidence of Coverage, which sets out how that plan charges for its extra benefits.

The Part B premium. $202.90 a month is paid to Medicare, not to the plan, and no plan cap has ever counted it. Over twelve months that is $2,434.80.

What that adds up to at the ceilings

Stacking the published federal maximums gives the outer edge of a year inside a plan that has chosen every ceiling available to it.

Two things about that table matter more than the totals. The first is that these are the ceilings federal rules permit, not what a typical plan sets. Many plans choose limits well below the mandatory band, and a plan's real numbers are printed in its own documents rather than inferred from a table like this one.

The second is that Original Medicare has no equivalent column. There is no figure to put in that row, because without supplemental coverage the number has no upper bound at all. A capped worst case and an uncapped one are different in kind, not in size, and that difference runs in Medicare Advantage's favor.

Part 5

The six month window that does not come back

This is the part of the decision that is genuinely one directional, and it has nothing to do with which coverage is better.

The Medigap Open Enrollment Period is a single six month period that begins in the first month a person has Part B and is 65 or older. Inside it, any Medigap policy sold in that state can be bought. A company cannot use medical underwriting to refuse the application because of health, and cannot charge more because of health.

Under current federal law it happens once. It does not reopen at 70, or after a diagnosis, or on leaving a Medicare Advantage plan. After it closes, federal law no longer requires any company to sell a Medigap policy at all, except in the specific situations that carry guaranteed issue rights. Medicare's own Medigap guide states it the same way: a one time enrollment period that does not repeat every year.

What happens after it closes

Outside the window and outside a guaranteed issue right, an application goes through medical underwriting. The company reads the health history and is free to decline it, or to accept it at a higher price. A person in good health at 72 may be sold a policy without difficulty. The same person after a cardiac event may not, and that is precisely the moment the coverage was wanted.

Two details that catch people

The window is tied to Part B, not to a birthday. Delaying Part B because of group health coverage from current employment also delays the window, which starts when Part B finally does.

Federal law generally does not require companies to sell Medigap to anyone under 65, so a person on Medicare through disability may find no policy available, or a costlier one, until they turn 65. Some states require companies to sell anyway.

The guaranteed issue rights that survive the window

Certain situations create a right to buy a policy with no underwriting even after the window has closed. Losing employer or union coverage is one. A plan leaving Medicare or leaving the service area is another. So is a Medigap company going bankrupt, or a policy ending through no fault of the person holding it, or a company breaking the marketing rules or misleading someone about what it sold them. The two trial rights in Part 6 sit on the same list.

That list is longer than most short summaries of it, this one included. Medicare publishes the full version, situation by situation, in its guide Choosing a Medigap Policy. Anyone whose coverage ended without them choosing it has reason to read the full list rather than assume the answer is no.

Every one of these rights runs on a clock, and the clock starts earlier than people expect. An application can go in as early as 60 days before the other coverage ends, and no later than 63 days after it ends. Some states extend these rights by a further twelve months, which is one more question for the State Insurance Department.

The waiting period, and the thing that cancels it

A company issuing a policy this way may still refuse to pay toward a pre-existing condition for up to six months. Two limits sit on that.

The first is what Medicare calls the look-back period: a condition can only be excluded if it was treated or diagnosed in the six months before the policy starts. The second matters more. At least six months of continuous prior creditable coverage removes the waiting period entirely, and the time spent inside the Medicare Advantage plan being left counts as creditable coverage. Someone leaving a plan they have held for a year and applying inside the 63 days is generally not facing a waiting period at all.

Even where a waiting period does apply, Original Medicare keeps paying its own share for the condition. What goes unpaid is the coinsurance the Medigap policy would otherwise have covered.

Part 6

The two trial rights and the deadlines on them

Federal rules carve out two escape hatches for people who try Medicare Advantage and want out. Both are called trial rights, both last twelve months, and both are single use.

Trial right one: dropped a Medigap policy to try Advantage

Someone who drops a Medigap policy to join a Medicare Advantage plan for the first time gets a single twelve month period to get that policy back, provided the same insurance company still sells it once they return to Original Medicare. If that company no longer sells it, the fallback is Medigap Plan A, B, C, D, F or G sold in that state, with one carve-out: Plans C and F are closed to anyone new to Medicare on or after January 1, 2020, who gets the right to buy Plan D or G instead.

Trial right two: joined Advantage at 65 instead of Original

Someone who joined a Medicare Advantage plan when first eligible for Part A at 65, having never held Medigap, can buy certain Medigap policies sold in their state if they switch to Original Medicare within the first year of joining. Again, which policies depends on whether they were new to Medicare on or after January 1, 2020.

Both rights also open a chance to join a Medicare drug plan, which matters because leaving an Advantage plan usually means leaving the drug coverage that was bundled inside it.

Three things that go wrong around these rights

The Medigap policy keeps billing. Most Medigap policies do not cancel themselves when someone joins a Medicare Advantage plan. Meanwhile Medigap cannot pay a Medicare Advantage plan's copayments, deductibles or premiums, so the policy charges full price for a year while covering nothing. Cancelling takes a phone call to the insurance company. Stopping the payments is not the same thing.

The twelve months run from joining, not from noticing. A plan year has to go badly before anyone knows it has gone badly, and a diagnosis in month eleven leaves very little of the window.

Anyone selling Medigap to a current Advantage member is breaking the law. It is illegal to sell a Medigap policy to a person enrolled in a Medicare Advantage plan unless they are switching back to Original Medicare. Medicare's guidance says to report it to the State Insurance Department.

Part 7

Networks, referrals and prior approval

The daily difference between the two doors is not the money. It is who has to agree before care happens.

The protection inside the network rules

Network restrictions are not absolute. When an in-network provider or benefit is not available, or cannot meet a patient's medical needs, the plan is required to help a member get any medically necessary covered service outside the network, at in-network cost sharing.

The exact wording carries the catch. The plan has to help, which means the protection runs through the plan rather than around it, and the mechanism for that is the organization determination below. Going out of network first and citing the rule afterwards is a far weaker position than asking for the decision in advance.

Asking the plan in advance

A plan can be asked, ahead of time, whether it will cover something and what it will cost. This is called an organization determination. The patient, a representative or the doctor can request one, spoken or in writing, and a fast decision can be requested when health requires it.

If the plan says no, it has to say no in writing, and that written denial carries appeal rights. A verbal no from a front desk is not a denial and cannot be appealed. Getting the answer in writing is what turns a refusal into something with a process attached.

Part 8

The two windows each year and what each one can do

Changes to Medicare coverage happen inside fixed windows, and the two annual ones are not interchangeable. They allow different moves to different people.

Special Enrollment Periods sit outside both of these and open for specific events, such as moving out of a plan's service area or losing other coverage.

The two notices that arrive before the window

Anyone in a Medicare Advantage plan receives two documents every autumn, and they are the only reliable warning that a plan has changed underneath them.

• The Annual Notice of Change lists what changes in January: costs, coverage, the yearly limit, the drug list. The plan sends a printed copy by September 30.
• The Evidence of Coverage is the full detail of what the plan covers and what it charges next year. The plan sends notice of it by October 15.

Plans are free to change coverage, costs and service areas each year, and free to leave Medicare entirely. When a plan leaves, its members have to join another plan or return to Original Medicare.

The thing neither window does

Neither of these windows carries a Medigap policy with it. Both of them allow a return to Original Medicare at will. Neither of them creates a right to buy the supplement policy that makes Original Medicare's open-ended 20 percent bearable. That right came from the six month window in Part 5, or from one of the trial rights in Part 6, or from a guaranteed issue situation, and from nowhere else under federal law.

Part 9

The one afternoon checklist

Everything below can be done in an afternoon, and the first item is the one that determines how much the rest of the list matters.

• Find the date Part B started. It is printed on the red, white and blue Medicare card.
• Count six months forward from the first month of Part B at age 65 or older. If that date has not passed, the Medigap window is still open and any policy sold in the state can be bought without a health question.
• Call the State Insurance Department and ask two things: whether the state adds Medigap enrollment rights beyond the federal six months, and whether companies in the state must sell to people under 65.
• Call the State Health Insurance Assistance Program. It is free, it is state specific, it does not sell anything, and the number is in the Medicare handbook and at Medicare.gov.
• If already in a Medicare Advantage plan, find the date of joining. If it was under twelve months ago and it was the first Advantage plan, a trial right may still be open.
• If a Medigap policy was dropped to join that plan, call the old insurance company and ask in writing whether the same policy can be reinstated inside the trial right, and at what price.
• Read the Annual Notice of Change when it arrives by September 30. Compare next year's premium, yearly limit, drug list and provider list against this year's.
• Write down the plan's in-network yearly limit and, if the plan pays anything out of network, the combined limit. Both are in the Evidence of Coverage.
• Check every prescription by name and dose against next year's drug list, and check every doctor against next year's network.
• If any coverage ended without it being a choice, through a company going bankrupt, a plan leaving the area or a company breaking the rules, read the guaranteed issue list in Medicare's Choosing a Medigap Policy before accepting that underwriting applies.
• Never cancel a Medigap policy by stopping payment. Call the company and cancel it, or it keeps billing while covering nothing.
• Note which window applies before making any change: October 15 to December 7 for anyone, January 1 to March 31 only for people already in an Advantage plan.