Medicare Part B Deductible and Coinsurance Explained

Most people breathe a sigh of relief when they qualify for Medicare, assuming their days of worrying about medical bills are over. Then the first Explanation of Benefits arrives, and they see terms like deductible and coinsurance staring back at them. Suddenly, the relief turns into confusion. What exactly is the Part B deductible? Why does a 20 percent coinsurance charge appear on a bill for a simple office visit? And why does it feel like Medicare pays less than expected? These are not trivial questions. For many beneficiaries living on fixed incomes, misunderstanding how Part B cost sharing works can lead to hundreds or even thousands of dollars in unplanned medical expenses each year.

This article breaks down the Medicare Part B deductible and coinsurance explained in plain language, with real numbers and practical examples. You will learn how the annual deductible works, when it resets, which services trigger the 20 percent coinsurance, and how supplemental coverage can dramatically reduce your out of pocket exposure. By the end, you should have a clear picture of what you can expect to pay for outpatient care under Original Medicare and what steps you can take to protect your budget.

How the Annual Part B Deductible Works

The Medicare Part B deductible is the amount you must pay out of pocket for covered services before Medicare begins to pay its share. Think of it as a yearly threshold you need to cross. Once you reach the deductible, Medicare starts covering its portion of the approved services, and you are then responsible for the coinsurance, typically 20 percent of the Medicare approved amount. The deductible applies only to Part B services, which include doctor visits, outpatient care, preventive services (with some exceptions), durable medical equipment, and certain lab work.

One of the most common misunderstandings is that the deductible is a one time cost. It is not. The Part B deductible resets every calendar year on January 1. That means even if you met the deductible in December, you start over with a fresh deductible in January. This annual reset can catch people by surprise, especially if they have ongoing medical needs. For example, if you see a specialist in early January before meeting the new deductible, you may be responsible for the full Medicare approved amount for that visit until the deductible is satisfied.

The exact deductible amount changes from year to year based on Medicare Trustees projections and legislative adjustments. For 2026, the Part B deductible is $257. That is a modest increase from previous years, but it is important to budget for it. The deductible applies to the Medicare approved amount, not the provider's full charge. If a doctor charges more than the approved amount, you may also be responsible for the difference, up to a limit, depending on whether the provider accepts Medicare assignment.

There are also exceptions to the deductible. Many preventive services, such as the annual wellness visit, flu shots, and certain cancer screenings, are covered by Medicare Part B with no deductible and no coinsurance. That means you can receive these services at no cost as long as you see a provider who accepts Medicare. This is a crucial distinction because it encourages beneficiaries to take advantage of preventive care without worrying about cost sharing. However, diagnostic services (like blood tests to investigate a symptom) are generally subject to the deductible and coinsurance.

To manage the deductible effectively, consider scheduling non urgent procedures later in the year if you have already met your deductible, or plan for the cost early in the year if you have ongoing conditions. If you are still working and have employer coverage, you may be able to delay Part B enrollment, but you should understand how that interacts with your deductible. Our guide on whether you need Medicare Part B if working explains those rules in detail.

The 20 Percent Coinsurance Rule and Which Services It Covers

After you meet the Part B deductible, Medicare generally pays 80 percent of the Medicare approved amount for covered services, and you pay the remaining 20 percent. This is the coinsurance. Unlike a copayment, which is a fixed dollar amount, coinsurance is a percentage, so your out of pocket cost varies with the cost of the service. For a $100 office visit, your coinsurance is $20. For a $1,000 outpatient procedure, your coinsurance is $200. There is no annual cap on this 20 percent coinsurance under Original Medicare, which is why supplemental coverage becomes so important.

The 20 percent coinsurance applies to a wide range of Part B services. Common examples include doctor visits (both primary care and specialists), outpatient surgery, diagnostic imaging (like MRI or CT scans), lab tests ordered for diagnosis, durable medical equipment (like wheelchairs or oxygen tanks), and some outpatient mental health services. It also applies to ambulance services and certain preventive services that are not on the no cost list. The list is extensive, and it is wise to check whether a specific service is subject to coinsurance before you receive it.

To illustrate how coinsurance works in practice, consider a beneficiary who needs a series of outpatient physical therapy sessions. Each session might have a Medicare approved amount of $150. After the deductible is met, the beneficiary pays $30 per session (20 percent), and Medicare pays $120. Over 20 sessions, that adds up to $600 in coinsurance. For someone on a tight budget, that is a significant sum. Now imagine a more expensive service, such as a colonoscopy that costs $2,000. The coinsurance would be $400. Without supplemental insurance, these costs can accumulate quickly.

It is also important to understand the difference between the coinsurance and excess charges. If a provider does not accept Medicare assignment, they can charge up to 15 percent more than the Medicare approved amount. That extra amount is called an excess charge, and you are responsible for it unless you have a Medigap plan that covers excess charges. Most Medigap plans do not cover excess charges, but Plan F and Plan G do. Always ask your provider whether they accept Medicare assignment to avoid surprise bills.

Another key point is that the 20 percent coinsurance applies to the Medicare approved amount, not the provider's billed amount. If a provider bills $500 but Medicare approves only $300, the coinsurance is calculated on the $300. The provider may then charge you the difference, but only if they do not accept assignment. This is why choosing providers who accept Medicare assignment is a smart financial move. It also helps to review your Explanation of Benefits carefully to ensure you are being charged correctly.

How Medigap and Medicare Advantage Reduce Part B Out of Pocket Exposure

Because Original Medicare has no out of pocket maximum, many beneficiaries look for ways to limit their financial risk. Two main options exist: Medicare Supplement Insurance (Medigap) and Medicare Advantage (Part C). Each works differently to reduce Part B costs, and understanding the trade offs is essential for making an informed decision.

Medigap plans are sold by private insurers and are designed to fill the gaps in Original Medicare coverage. Depending on the plan letter, Medigap can cover some or all of the Part B deductible, the 20 percent coinsurance, and even hospital coinsurance. For example, Medigap Plan G covers the Part B coinsurance and hospital coinsurance but does not cover the Part B deductible. Plan F, which is no longer available to newly eligible beneficiaries, covers both the deductible and coinsurance. Plan N covers the coinsurance but requires small copayments for some office visits and emergency room visits. With a Medigap plan, you can see any provider who accepts Medicare, and you generally do not need referrals for specialists. The trade off is that Medigap premiums can be higher, especially for plans with more comprehensive coverage.

Medicare Advantage plans, on the other hand, are an all in one alternative to Original Medicare. They are offered by private insurers and often include prescription drug coverage and extra benefits like dental, vision, and hearing. Medicare Advantage plans typically have lower premiums than Medigap, but they use networks of providers and have copayments and coinsurance that vary by plan. Some Medicare Advantage plans have a $0 deductible for Part B services, but they may charge copayments for doctor visits and other services. The out of pocket maximum for Medicare Advantage plans is capped, which provides financial protection, but the cap can be high. It is important to compare the total cost of care, not just the premium.

To help you compare these options, here are three common ways beneficiaries manage Part B costs:

• Original Medicare alone: You pay the Part B deductible and 20 percent coinsurance with no cap. This option offers the most flexibility but the highest financial risk.
• Original Medicare plus Medigap: You pay a monthly Medigap premium, but your out of pocket costs for Part B services are significantly reduced or eliminated. This is ideal if you want predictable costs and broad provider access.
• Medicare Advantage: You may pay a low or $0 monthly premium, but you will have copayments and coinsurance when you receive care. The plan has an annual out of pocket maximum, which protects you from catastrophic costs.

When evaluating Medigap plans, it is helpful to work with a licensed agent who can explain the differences between plan letters and help you find the best fit for your health needs and budget. You can also use online resources to compare plans. For a broader look at insurance options beyond Medicare, including auto, home, and life insurance, you might visit InsuranceShopping.com for educational guides and comparison tools.

Examples of Total Part B Costs for a Typical Year

To make the numbers concrete, let us walk through a few scenarios of what a beneficiary might pay for Part B services in a typical year. These examples assume the 2026 Part B deductible of $257 and a 20 percent coinsurance after the deductible is met. They also assume the beneficiary sees providers who accept Medicare assignment.

Scenario 1: Minimal healthcare use. Maria is in good health and sees her doctor twice a year for routine checkups. Each visit has a Medicare approved amount of $150. She also has one preventive screening that is covered at no cost. Her total Part B costs for the year: she pays the first $257 of approved charges toward the deductible. Since her two visits total $300, she pays $257 for the first visit (deductible) and then 20 percent of the remaining $43, which is $8.60. For the second visit, she pays 20 percent of $150, which is $30. Her total out of pocket for Part B services is $257 + $8.60 + $30 = $295.60. That is a manageable amount for many people.

Scenario 2: Moderate healthcare use. James has high blood pressure and sees a specialist quarterly. Each specialist visit has an approved amount of $200. He also has an annual colonoscopy that costs $1,500. His total approved charges for the year: four specialist visits at $200 each = $800, plus the colonoscopy at $1,500 = $2,300. He pays the first $257 toward the deductible. Then he pays 20 percent of the remaining $2,043, which is $408.60. His total out of pocket is $257 + $408.60 = $665.60. That is still reasonable, but it is a noticeable expense.

Scenario 3: High healthcare use. Linda needs outpatient surgery and follow up physical therapy. Her approved charges total $15,000 for the year. She pays the $257 deductible, then 20 percent of the remaining $14,743, which is $2,948.60. Her total out of pocket is $3,205.60. Without supplemental insurance, that is a significant financial burden. If Linda had a Medigap Plan G, she would only be responsible for the $257 deductible, and the plan would cover the $2,948.60 coinsurance. That is why many beneficiaries with ongoing health issues choose Medigap.

These examples show that while the Part B deductible is a fixed and relatively small amount, the 20 percent coinsurance can add up quickly, especially for those who need specialized care. It is important to budget for these costs and consider supplemental coverage if you anticipate needing more than routine care.

Where to Compare Plans That Lower Part B Costs

If you are looking to reduce your Part B out of pocket costs, the first step is to understand the options available in your area. Medicare Advantage and Medigap plans vary by ZIP code, and premiums, copayments, and provider networks differ from plan to plan. A plan that works well for your neighbor may not be the best fit for you. That is why comparing plans side by side is essential.

NewMedicare.com offers a free, no obligation tool to compare Medicare Advantage, Medigap, and Part D plans in your area. By entering your ZIP code, you can see a list of plans available to you, along with estimated costs and benefits. You can also request a complimentary consultation with a licensed insurance agent who can answer your questions and help you enroll in the plan that best meets your needs. The service is designed to be educational and unbiased, so you can make an informed decision without pressure.

When comparing plans, pay attention to the following factors: the monthly premium, the deductible (if any), the copayments or coinsurance for services you expect to use, the out of pocket maximum, and whether your doctors and hospitals are in the network. For Medigap plans, check which plan letters are available in your state and whether the plan covers the Part B deductible and coinsurance. Also consider the insurer's reputation and rate increase history. A licensed agent can help you navigate these details and find a plan that fits your budget and healthcare needs.

Remember that Medicare Part B deductible and coinsurance explained here is just the beginning. Your overall healthcare costs depend on many factors, including your health status, the providers you see, and the plans you choose. Taking the time to compare options and understand the costs can save you money and give you peace of mind. If you have questions, do not hesitate to reach out to a trusted resource or speak with a licensed agent who can provide personalized guidance.

In summary, the Part B deductible is an annual threshold you must meet before Medicare pays its share, and the 20 percent coinsurance is your share of the approved amount after the deductible. These costs can add up, but supplemental coverage like Medigap or Medicare Advantage can help limit your exposure. By planning ahead and comparing plans, you can manage your healthcare budget effectively and focus on what matters most: your health.