Key Takeaways

• Medicare Part B in 2025 comes with rules and costs that may be surprising if you haven’t looked closely. Missing deadlines or assuming coverage is automatic could cost you.

• While Part B is optional, delaying enrollment without employer coverage may result in lifelong late penalties and long wait times for coverage to start.

What Medicare Part B Actually Covers

Medicare Part B is known as “medical insurance,” and it covers outpatient care, including:

• Doctor visits (primary and specialists)

• Preventive services (like screenings and vaccines)

• Lab work and imaging (like blood tests, MRIs, or X-rays)

• Durable medical equipment (such as wheelchairs or oxygen)

• Outpatient mental health services

• Some home health services

This coverage is vital for managing your ongoing health needs outside a hospital setting. But it doesn’t cover everything—and what it does cover usually comes with cost-sharing responsibilities.

How Much Does Medicare Part B Cost in 2025?

The standard monthly premium for Part B in 2025 is $185. However, your actual premium might be higher based on your income. This adjustment is called the Income-Related Monthly Adjustment Amount (IRMAA).

• If your income exceeds $106,000 (individual) or $212,000 (joint filers), you’ll pay more.

• The amount is based on your modified adjusted gross income from your 2023 tax return.

Besides the premium, you must also pay an annual deductible—$257 in 2025. Once you meet the deductible, Medicare typically covers 80% of approved costs, and you’re responsible for the remaining 20% with no annual out-of-pocket cap.

Enrollment Is Not Always Automatic

One common misconception is that you’ll be automatically enrolled in Part B when you turn 65. That only happens if you’re already receiving Social Security or Railroad Retirement Board benefits at that time.

If you’re not receiving those benefits, you must actively sign up. The timeline is strict:

• Initial Enrollment Period (IEP): Begins 3 months before your 65th birthday month, includes your birthday month, and ends 3 months after. That’s a 7-month window.

• General Enrollment Period (GEP): Runs from January 1 to March 31 each year. Coverage begins the following month.

• Special Enrollment Period (SEP): Applies if you had creditable employer coverage after turning 65. You have 8 months to enroll after the coverage ends.

If you miss your enrollment period without qualifying for an SEP, you could face a late enrollment penalty and a coverage delay.

The Late Enrollment Penalty Is Long-Term

The penalty for late enrollment in Part B is not a one-time fee. It’s a permanent increase in your monthly premium:

• 10% for each full 12-month period you were eligible but didn’t enroll.

• The penalty is added to your premium every month for as long as you have Part B.

For example, if you waited 3 full years without employer coverage, your penalty would be 30% on top of the standard premium, for life.

Coordination With Employer Coverage Can Get Complicated

If you or your spouse are still working and covered by a group health plan, you may qualify for a Special Enrollment Period and can delay Part B without penalty. But there are conditions:

• The employer must have 20 or more employees for the coverage to count as primary.

• COBRA and retiree coverage are not considered creditable coverage for delaying Part B.

When the employment ends—or the coverage does—you’ll need to act fast. You only have 8 months from that date to enroll in Part B without a penalty.

Medicare Part B and Medicare Advantage Are Not the Same

Medicare Advantage plans, also called Part C, often include benefits from both Part A and Part B. But enrolling in a Medicare Advantage plan does not replace the need to be enrolled in Part B. In fact, you must be enrolled in both Part A and Part B to join a Medicare Advantage plan.

This catches many people off guard. Some assume they can skip Part B if they’re enrolling in a private plan. That’s incorrect and could leave you without valid Medicare coverage.

Out-of-Pocket Costs Add Up Quickly

Even with Medicare Part B, you still pay for care:

• 20% coinsurance after the deductible for most services

• No out-of-pocket maximum under Original Medicare

If you require regular outpatient treatments, physical therapy, or medical equipment, these costs can escalate fast. Many people pair Part B with supplemental insurance (like Medigap) or a Medicare Advantage plan that includes caps on out-of-pocket expenses.

Preventive Services Can Save You Money—If You Use Them

Medicare Part B covers a broad range of preventive services at no additional cost to you if the provider accepts assignment:

• Annual wellness visits

• Flu shots and COVID-19 vaccines

• Screenings for cancer, diabetes, and cardiovascular conditions

• Bone density tests

These services are often underused, but they’re designed to catch problems early, which reduces long-term costs and improves health outcomes.

You Can Switch or Adjust Coverage—But Only at Certain Times

If your needs change, you’re not stuck with your current coverage forever. You have annual opportunities to review or make changes:

• Medicare Open Enrollment: October 15 to December 7. You can switch between Original Medicare and Medicare Advantage or change Part D plans.

• Medicare Advantage Open Enrollment: January 1 to March 31. If you’re already in a Medicare Advantage plan, you can switch to a different one or return to Original Medicare.

Outside of these periods, changes are only allowed if you qualify for a Special Enrollment Period.

How Part B Works With Other Types of Coverage

Medicare Part B can coordinate with other forms of insurance, but the rules vary:

• TRICARE or VA benefits: You may still need Part B to get complete coverage.

• Marketplace insurance: Once you’re eligible for Medicare, you’re no longer eligible for premium subsidies under ACA plans.

• Retiree insurance: You still need Part B to avoid gaps, and it typically pays secondary.

Understanding how your other insurance fits with Medicare is essential to avoid denied claims or unexpected bills.

The Coverage Gaps You Might Not Expect

Many people assume Medicare Part B covers all medical needs. That’s not the case. It doesn’t cover:

• Long-term custodial care

• Dental exams, dentures, or most dental work

• Eye exams related to prescription glasses

• Hearing aids and fitting exams

• Most prescription drugs (you need Part D or another drug plan for that)

To avoid financial surprises, you’ll need to plan for how to cover these services—either out of pocket or through additional insurance.

There’s No Family Coverage Option

Unlike employer plans, Medicare doesn’t have a family option. Each person must enroll individually. If you and your spouse turn 65 at different times, your enrollment timelines will differ. You cannot combine coverage under a single plan.

Understanding this helps you plan your household health expenses more realistically.

The Importance of Keeping Records and Notices

Once you’re enrolled, you’ll receive various notices—such as your Medicare Summary Notice (MSN), IRMAA determination letters, and coverage updates.

Keep these documents organized. They can help you:

• Track billing errors

• Appeal premium surcharges

• Verify enrollment dates

These details matter, especially if you later apply for a Special Enrollment Period or appeal a late enrollment penalty.

Why It Pays to Plan Ahead With Medicare Part B

You shouldn’t wait until you’re nearing 65 to think about Medicare Part B. Start reviewing your coverage options at least 6 to 12 months in advance. This allows you to:

• Check your eligibility for automatic enrollment

• Assess how employer coverage interacts with Medicare

• Evaluate your financial readiness for premiums and coinsurance

Early planning gives you time to ask questions and avoid costly mistakes.

Make Confident Decisions About Your Medicare Coverage

Medicare Part B may look straightforward at first glance, but as you’ve seen, it’s filled with deadlines, costs, exceptions, and coordination rules that aren’t always obvious. Skipping over these details can result in long-term penalties or inadequate coverage when you need it most.

You don’t have to figure it all out alone. Reach out to a licensed agent listed on this website for help reviewing your Medicare options and getting answers tailored to your situation.