Medicare Plan B pays for doctor visits and outpatient care that Original Medicare Part B does not fully cover

Medicare Plan B, officially called Medigap Plan B, is supplemental insurance sold by private companies. It works alongside Original Medicare (Parts A and B) to cover costs that Medicare itself leaves you responsible for — like copayments, coinsurance, and deductibles. Plan B is one of ten standardized Medigap plans, each with a different set of covered services.

Plan B specifically covers your Part B deductible (the amount you pay before Medicare starts paying), 20% coinsurance for doctor visits and outpatient services after you meet that deductible, and some hospital costs. It does not cover prescription drugs, dental, vision, or hearing aids. If you need those, you would purchase them separately or through a Medicare Advantage plan instead.

The main reason to choose Plan B over other Medigap options is cost: it has the lowest monthly premium of the standardized plans because it covers fewer services. The trade-off is that you still pay out-of-pocket for things like skilled nursing facility coinsurance and foreign travel emergencies.

Key Takeaways

  • Plan B covers your Part B deductible and 20% coinsurance for doctor visits and outpatient hospital care, but not prescription drugs or routine dental and vision.
  • You must be enrolled in Original Medicare Parts A and B to buy Plan B; it does not work with Medicare Advantage plans.
  • Plan B premiums vary by insurance company and your location, but it is the least expensive standardized Medigap option.
  • You have a six-month window after turning 65 and enrolling in Part B to buy Plan B without medical underwriting or higher premiums for pre-existing conditions.

What Plan B Actually Covers

Plan B covers your Part B deductible, which is the fixed amount you pay out of pocket before Medicare starts sharing costs. In 2024, that deductible is $240 per year, though this amount changes annually. Once you meet it, Plan B pays 20% of what Medicare approves for doctor visits, lab tests, imaging, and outpatient hospital services — you pay nothing more for those services.

Plan B also covers Part A coinsurance for hospital stays. If you stay in the hospital longer than 60 days in a benefit period, Medicare stops covering the full cost and you owe coinsurance. Plan B pays that coinsurance for days 61 through 90, and for an additional 60 "lifetime reserve days" that Medicare provides. After those days, you pay the full cost.

Plan B does not cover skilled nursing facility coinsurance (the 20% you owe after day 20 of a nursing home stay), blood transfusions, or excess charges when a doctor does not accept Medicare's approved amount. It also does not cover prescription drugs, dental work, vision care, hearing aids, or emergency care outside the United States.

How Plan B Differs From Other Medigap Plans

Medigap Plan A is the only standardized plan cheaper than Plan B, but it covers less: Plan A does not cover your Part B deductible at all. Plan C, D, G, and M all cover more services than Plan B and therefore cost more per month. Plan G, for example, covers the Part B deductible plus excess charges, which Plan B does not.

The choice between Plan B and other options depends on how much you use healthcare and what you can afford monthly. If you see doctors frequently or worry about excess charges, a more comprehensive plan may save you money overall. If you are healthy and want the lowest premium, Plan B is the least expensive entry point into Medigap coverage.

Plan B is different from Medicare Advantage (Part C), which is an alternative to Original Medicare sold by private insurers. Advantage plans often include prescription drug coverage and dental benefits but require you to use in-network doctors and may have higher out-of-pocket limits. You cannot have both Plan B and an Advantage plan at the same time.

When You Can Buy Plan B Without Medical Questions

The best time to buy Plan B is during your Medigap open enrollment period, which lasts six months starting the first day of the month you turn 65 and enroll in Medicare Part B. During this window, insurance companies cannot deny you coverage or charge you more because of pre-existing conditions. This is called may provide issue rights.

If you miss this six-month window, you can still buy Plan B, but the insurance company may ask health questions, deny you coverage, or charge you a higher premium based on your medical history. Some states have additional protections that extend may provide issue rights, but these vary. If you are outside the open enrollment period, contact your state's insurance commissioner's office to learn what protections explore to you.

You must be enrolled in both Medicare Part A and Part B to buy Plan B. If you have not enrolled in Part B yet, you can do so during the Initial Enrollment Period (the three months before, the month of, and the three months after your 65th birthday) or during the General Enrollment Period (January 1 through March 31 each year, with coverage starting July 1).

How Much Plan B Costs

Plan B premiums vary significantly by insurance company and your location. There is no single "Plan B price" — the same plan costs different amounts depending on which insurer you choose and which state you live in. In some areas, Plan B premiums range from $80 to $150 per month, but this varies widely and changes year to year.

Insurance companies use three different pricing methods for Medigap plans: community-rated (everyone in your area pays the same), age-rated (your age affects the price), and issue-age-rated (the price depends on your age when you first buy the plan). Plan B premiums may increase over time due to inflation and claims experience, not because you are getting older, though this depends on the company's pricing method.

To find the lowest Plan B premium in your area, contact multiple insurance companies directly or use your state's health insurance counselor, who can compare plans for free. The Centers for Medicare & Medicaid Services (CMS) also publishes a list of Medigap insurers by state on Medicare.gov.

Plan B Versus Plan A: Which Costs Less Overall

Plan A has a lower monthly premium than Plan B because it covers fewer services. Plan A does not cover your Part B deductible, so you pay that $240 out of pocket each year. Plan B covers it, so you save $240 annually but pay a higher monthly premium.

Whether Plan A or Plan B costs less overall depends on how much healthcare you use. If you rarely see a doctor, Plan A's lower premium may win out even though you pay the Part B deductible. If you see doctors regularly, Plan B's coverage of the deductible and coinsurance usually saves you money despite the higher premium. Run the numbers for your situation: add up your expected out-of-pocket costs under each plan, then add the annual premiums to see which totals less.

How to Enroll in Plan B

To buy Plan B, contact insurance companies directly by phone or through their websites. You do not enroll through Medicare; private insurers sell Medigap plans. Have your Medicare card handy when you call, as the company will need your Medicare number and the date your Part B coverage started.

Ask each company about their Plan B premium, any waiting periods for coverage to start, and whether they use community-rating, age-rating, or issue-age-rating. Some companies offer discounts for paying annually instead of monthly, or for setting up automatic payments. Compare at least three companies before deciding.

Once you choose a plan and the company approves you, your coverage typically starts on the first of the following month. Your first premium payment may be due before coverage begins. Keep your Original Medicare coverage active while you wait for Plan B to start — do not cancel it.

Frequently Asked Questions

Can I switch from Plan B to a different Medigap plan later?

Yes, but you may face medical underwriting and higher premiums if you switch outside your initial six-month open enrollment period. Some states allow switching without medical questions during certain windows. Contact your state insurance commissioner's office to learn your state's rules before switching.

Does Plan B cover prescription drugs?

No. Plan B does not include prescription drug coverage. You must enroll in a separate Medicare Part D plan (offered by private insurers) to cover medications. You can enroll in Part D during your Initial Enrollment Period or during the annual open enrollment period in October.

What happens if I do not buy Plan B and just keep Original Medicare?

You remain covered by Medicare Parts A and B, but you pay all deductibles, coinsurance, and copayments out of pocket. This can add up quickly if you have a hospital stay or see doctors frequently. Many people find that Medigap coverage, even Plan B, saves them money overall.

Can I have Plan B and a Medicare Advantage plan at the same time?

No. You must choose either Original Medicare with Medigap (Plan B) or Medicare Advantage. If you enroll in an Advantage plan, your Medigap coverage ends. If you later switch back to Original Medicare, you may not be able to buy Plan B without medical underwriting.

What if my doctor does not accept Medicare?

Plan B does not cover excess charges when a doctor does not accept Medicare's approved amount. If a doctor charges more than Medicare allows, you pay the difference. Ask your doctor whether they accept Medicare assignment before scheduling appointments.