Medicare · Cornerstone
Medicare supplement open enrollment: your guaranteed-issue window
Last reviewed October 9, 20267 min readBy the Goodsurance editorial team Reviewed by the Goodsurance editorial team
Medigap is the informal name for Medicare supplement insurance, private policies that fill the gaps Original Medicare (Part A and Part B) leaves behind. Those gaps include the Part A inpatient deductible, which is $1,736 per benefit period in 2026, and the Part B coinsurance, which is 20% of covered costs with no annual ceiling. A Medigap policy picks up some or all of those costs depending on which standardized letter plan you buy.
1What Medicare supplement open enrollment actually is
The open enrollment period exists because Congress wanted a guaranteed-access window to go alongside Medicare itself. Without it, private insurers could simply decline to cover anyone with a pre-existing condition, which would make supplemental coverage inaccessible to many of the people who need it most.
During the open enrollment window, federal law bars insurers from medical underwriting. They cannot turn you down or charge you more because of a prior hospital stay, a chronic condition, or the drugs you take. How a premium rises with age later (community, issue-age, or attained-age pricing) is a separate choice each insurer makes, and it is worth asking about. That protection disappears the moment the window closes for people in most states.
In short: the open enrollment window is a federally mandated, one-time guaranteed-issue access period tied to your age and your Part B enrollment date.
2When the window opens and exactly how long it lasts
According to Medicare.gov, the Medigap open enrollment period is six months long. It starts on the first day of the month in which you are both 65 or older and enrolled in Part B. Both conditions must be true at the same time; the clock does not start from just turning 65 if you have not yet signed up for Part B.
A few timing scenarios come up often:
You enroll in Part B at 65. The window opens on the first of your birthday month and runs for exactly six calendar months. If your birthday is in March, the window runs March 1 through August 31.
You delay Part B past 65 while covered by an employer plan. If you later enroll in Part B under the eight-month Special Enrollment Period (SEP) that begins when your employment or employer coverage ends, whichever comes first, your Medigap open enrollment window starts when your Part B coverage begins, regardless of your age at that point. The six-month duration is the same.
You are under 65 and on Medicare because of a disability. Federal law does not require insurers to sell Medigap to people under 65. Some states do require it, with varying rules on timing and plan availability. If you are in this situation, contact the State Health Insurance Assistance Program (SHIP) in your state for guidance on what local protections apply.
COBRA and retiree coverage are not active employer coverage. Neither one counts as active employer coverage for the Part B Special Enrollment Period or the late penalty. If you put off Part B while on COBRA or a retiree plan, you can owe the Part B penalty and have to wait for the General Enrollment Period to sign up. Your Medigap window then starts whenever Part B finally begins, which can be later than you planned.
In short: the clock starts when both conditions are met, 65 or older and Part B enrolled, and it runs for exactly six months with no extensions.
3What you can buy during open enrollment
During open enrollment, an insurer must sell you any Medigap policy it offers in your state. Federal rules standardize Medigap plans by letter: Plans A, B, C, D, F, G, K, L, M, and N. Massachusetts, Minnesota, and Wisconsin standardize their plans differently. Each letter plan offers the same core benefits regardless of which insurer sells it, so comparison shopping comes down to premium, insurer financial strength, and rate-increase history.
A few plan details worth knowing:
- Plan F and Plan C are only available to people who first became eligible for Medicare before January 1, 2020. If you became eligible on or after that date, those plans are not an option.
- Plan G is now the most comprehensive plan available to new Medicare enrollees, covering everything Plan F covered except the Part B deductible, which is $283 in 2026.
- Plan N covers most costs but requires a copay of up to $20 for some office visits and up to $50 for emergency room visits that do not result in an inpatient admission. Plan N also does not cover Part B excess charges, which are the additional amounts non-participating providers can bill above the Medicare-approved rate, up to 15%.
- High-deductible versions of Plans F and G are available in many states (the F version only to people eligible before 2020). In 2026, the CMS-set high-deductible amount for those plans is $2,950, after which the plan pays 100% of covered costs.
Premiums vary by insurer, your age, and where you live. The open enrollment period means you receive the best available rate for your age from each insurer during this window, not that every insurer charges the same amount. Shopping multiple carriers during this window is worth the time.
In short: all standardized letter plans available in your state are accessible during open enrollment; Plan G is the most comprehensive option for most new enrollees, and the high-deductible version at $2,950 in 2026 is a lower-premium alternative.
4What happens if you miss the window
Missing the open enrollment period does not close the door on Medigap permanently, but it changes the terms significantly. Outside of protected enrollment periods, most states allow insurers to use medical underwriting, meaning they can:
- Charge a higher premium based on your health status
- Exclude coverage for pre-existing conditions for a waiting period
- Decline your application entirely
If you are in good health when you apply outside of open enrollment, underwriting may not affect you much. If you have ongoing health conditions, the rate difference can be substantial, and denial is a real possibility in states that do not have additional protections.
Guaranteed issue rights are the main exception. Federal law gives you a guaranteed issue right, meaning the right to buy certain Medigap plans without underwriting, in specific situations. These include when your Medicare Advantage (Part C) plan leaves your area or stops covering your area, when you move out of your plan's service area, or when a Medigap insurer goes bankrupt. These rights are narrow and situation-specific.
In short: missing open enrollment puts you at the mercy of underwriting in most states, though federal guaranteed issue rights cover a defined set of qualifying life events.
5State-level protections beyond the federal window
Some states have extended Medigap access beyond the federal baseline, and the rules differ enough that it is worth understanding them by category rather than assuming your state is one of them.
Year-round guaranteed issue states. A few states, including New York and Connecticut, require insurers to sell Medigap at any time of year with no medical underwriting. This effectively makes every month an open enrollment period for residents of those states.
Plan-switching states. Some states, such as Washington, let people who already have Medigap switch plans without full underwriting, within limits.
Birthday-rule states. A growing group of states, including California and Oregon, let Medigap enrollees switch to a plan with equal or lesser benefits around their birthday each year without underwriting. The number of states changes often, and the windows and qualifying plans vary widely by state.
If you live in one of these states, your options for switching or enrolling outside of the federal window are meaningfully better. Contact your state insurance department or SHIP counselor to get the exact rules that apply where you live.
In short: year-round, birthday-rule, and plan-switching protections exist in a meaningful number of states, but the rules differ in kind, not just degree, so check your state specifically.
6How to use the open enrollment window strategically
The open enrollment period is not just a deadline to meet; it is the best possible moment to make a long-term cost decision. A few practical strategies:
Apply before Part B starts, if possible. Many insurers let you apply before your Part B start date. Applying early means coverage can start the same day as Part B, with no gap.
Compare rate-increase histories, not just current premiums. Two plans with the same letter and similar starting premiums can diverge significantly over a decade if one insurer raises rates more aggressively. Your state insurance department maintains rate-filing records that show historical increases by insurer.
Think about the Part D interaction. Medigap does not cover prescription drugs, and it does not work with Medicare Advantage. You will need a separate Part D (prescription drug) plan. In 2026, the annual out-of-pocket cap on covered Part D drugs is $2,100. No Part D plan may set a deductible above $615 in 2026. Buying Medigap and Part D together as a pair is the standard approach for people staying in Original Medicare.
Factor in the Part B late-enrollment penalty if you delayed. If you enrolled in Part B late without qualifying coverage, the Part B penalty adds 10% for each full 12-month period of delay, permanently. That higher premium is part of your ongoing cost calculation alongside whatever Medigap premium you choose.
In short: apply early, compare rate histories alongside premiums, and coordinate your Medigap choice with a Part D plan from the start.
Common questions about Medicare
Quick answers to common questions
Tap any question to expand. Each question links to a fuller standalone answer.
Does Medicare pay for hearing aids
Original Medicare does not cover hearing aids or fittings.
Some Medicare Advantage plans may include a hearing benefit, but what they cover varies by plan.
Does Medicare cover ambulance services?
Yes, in limited situations.
Medicare Part B covers emergency ambulance transportation when traveling any other way could endanger your health, taking you to the nearest appropriate hospital or facility. You pay 20% of the Medicare-approved amount after the $283 Part B deductible in 2026. Air ambulance is covered only when ground transport cannot reach you or would take too long. Non-emergency ambulance trips, for example to dialysis, are covered only when a doctor provides a written order stating they are medically necessary. Medicare does not cover ambulance rides taken purely for convenience.
Does Medicare cover skilled nursing facility care?
Yes, on a short-term basis.
Medicare Part A covers skilled nursing facility (SNF) care after a qualifying inpatient hospital stay of at least 3 days, when you need daily skilled care like nursing or therapy. In 2026 you pay $0 for days 1 through 20 of each benefit period, $217 per day for days 21 through 100, and all costs after day 100. Coverage is for skilled care while you recover, not for long-term or custodial care (help with daily activities like bathing or dressing), which Medicare does not cover. Long-term nursing home care is generally paid through Medicaid or private funds.
Does Medicare cover physical therapy?
Yes.
Medicare Part B covers outpatient physical therapy that is medically necessary to treat your condition. You pay 20% of the Medicare-approved amount after the yearly Part B deductible ($283 in 2026). There is no longer a hard dollar cap on therapy, but once your physical and speech therapy together pass $2,480 in 2026, your therapist must add a note (called a KX modifier) confirming you still need care. Claims above $3,000 may be reviewed for medical necessity. Part A covers physical therapy you receive as a hospital inpatient or in a skilled nursing facility. A doctor or therapist must set up and regularly review your plan of care.
Does Medicare cover mental health services?
Yes.
Medicare covers mental health care across its parts in 2026. Part B covers outpatient services like therapy, counseling, and visits with psychiatrists, psychologists, and clinical social workers, and since 2024 it also covers marriage and family therapists and mental health counselors. You pay 20% of the Medicare-approved amount after the $283 deductible, and one depression screening each year is free. Part A covers inpatient mental health care, with a lifetime limit of 190 days in a freestanding psychiatric hospital. Part D covers most mental health medications. Many of these services are also available by telehealth, and Medicare Advantage plans cover at least the same benefits.
Does Medicare cover chiropractic care?
Partly.
Medicare Part B covers one specific chiropractic service: manual manipulation of the spine to correct a subluxation (when one or more bones of the spine are out of position) that a doctor confirms is medically necessary. You pay 20% of the Medicare-approved amount after the $283 Part B deductible in 2026. Medicare does not cover other services a chiropractor might offer, such as X-rays, massage therapy, acupuncture, or routine wellness visits, so you would pay the full cost for those. Some Medicare Advantage plans include extra chiropractic or wellness benefits beyond this.
Does Medicare cover home health care?
Yes, when you qualify.
Medicare Parts A and B cover home health care if a doctor certifies that you are homebound (leaving home takes a major effort) and need part-time skilled care, such as skilled nursing, physical therapy, occupational therapy, or speech therapy. A Medicare-certified home health agency must provide the care under a plan your doctor reviews. You pay $0 for covered home health visits in 2026, and 20% for any durable medical equipment. Medicare does not cover 24-hour home care, meal delivery, or homemaker services like cleaning when that is the only care you need.
Does Medicare cover vision care?
Mostly no for routine care.
In 2026, Original Medicare does not cover routine eye exams for glasses or contact lenses, and it does not pay for the glasses or contacts themselves. It does cover some medical eye care: yearly glaucoma screenings for people at high risk, diabetic retinopathy exams, treatment for eye diseases, and cataract surgery (including one pair of standard glasses or contacts afterward). For those covered services you pay 20% after the $283 Part B deductible. Many Medicare Advantage plans add a routine vision benefit covering eye exams and an allowance for glasses.
Does Medicare cover hearing aids?
Original Medicare does not cover hearing aids or the exams used to fit them.
Some Medicare Advantage plans include a hearing benefit, but coverage varies by plan.
Does Medicare cover diabetes supplies and testing?
Yes.
In 2026 Medicare covers most diabetes care across two parts. Part B (outpatient care and equipment) covers blood sugar monitors, test strips, lancets, and continuous glucose monitors (CGMs) as durable medical equipment, plus diabetes screenings and a self-management training program. You pay 20% of the Medicare-approved amount after the $283 Part B deductible. Part D (drug coverage) covers insulin and related supplies like syringes, and in 2026 your insulin is capped at $35 for a month's supply. If you have a Medicare Advantage plan, it covers at least the same diabetes benefits, sometimes with added extras.
Does Medicare cover durable medical equipment?
Yes.
Medicare Part B covers durable medical equipment (DME): reusable medical gear your doctor prescribes for use at home, such as wheelchairs, walkers, hospital beds, oxygen equipment, CPAP machines, and blood sugar monitors. You pay 20% of the Medicare-approved amount after the $283 Part B deductible in 2026, and Medicare pays the other 80%. To be covered, the item must be ordered by a Medicare-enrolled doctor and supplied by a Medicare-enrolled supplier, and some items are rented rather than bought. Equipment meant mainly for use outside the home, or only for comfort or convenience, is not covered.
Which is better, Medigap or Medicare Advantage?
Neither is better for everyone; they suit different needs.
Medigap (also called Medicare Supplement, a private policy that pairs with Original Medicare) lets you see any doctor nationwide who accepts Medicare with no network and very predictable out-of-pocket costs, but you pay a monthly Medigap premium and add a separate Part D drug plan. Medicare Advantage (Part C, your Medicare benefits through a private plan) often has a lower or $0 plan premium, bundles drug coverage and extras like dental and vision, and caps your yearly out-of-pocket costs, but uses provider networks and may require prior approval. People who travel, want maximum doctor freedom, and prefer steady costs often lean Medigap; people who want low premiums, extras, and a network they are comfortable with often lean Medicare Advantage. With both, you still pay the Part B premium ($202.90 per month in 2026). To find out which fits your situation, reach out to a licensed Goodsurance advisor at 1-888-301-8091 (TTY 711), Mon to Fri 8 am to 5 pm PT.