Medicare B and Medicare D serve different roles in your healthcare coverage. Understanding how they work helps you choose the right plan elements for your situation.
This guide breaks down eligibility, costs, and what each part covers so you can make confident decisions.
| Plan Part | Type | Typical Monthly Cost | What It Covers |
|---|---|---|---|
| Medicare B | Medical Insurance | Standard premium $174.70 in 2025, higher incomes pay more | Doctor visits, outpatient care, preventive services, durable medical equipment |
| Medicare D | Prescription Drug Plan | Varies $15–$100+ per month, plans charge deductibles and copays | Retail prescription drugs, multiple tiers, preferred and nonpreferred drugs |
| Enrollment Timing | Initial window and general enrollment | Possible late penalties if you delay without creditable coverage | Coverage start dates differ by election period |
| Key Overlap | Ordering and status checks | Use the same Medicare account to view both parts | Confirm plan details and formulary updates each year |
How Medicare B Works and What It Covers
Medicare B is medical insurance that helps pay for services outside of hospital stays. It focuses on outpatient care, which means care you receive without being admitted overnight.
Under Medicare B, you can visit doctors, specialists, and clinics for checkups, tests, and treatments. Covered services include preventive care such as vaccines and screenings, which can lower long term costs.
Medicare B also covers durable medical equipment like wheelchairs and home oxygen. You usually pay a monthly premium, an annual deductible, and 20 percent of approved amounts for many services after meeting the deductible.
How Medicare D Works and What It Covers
Medicare D provides prescription drug coverage through private plans approved by Medicare. Each plan maintains its own formulary, which is a list of covered drugs organized into cost tiers.
You choose a plan that matches the drugs you take, and you pay a monthly premium plus deductibles and copays or coinsurance. Coverage gaps, like the coverage gap (often called the donut hole), have changed over time, so review your plan details each year.
With Medicare D, you must stay in the plan network for retail prescriptions to get full benefits, and plans can change their formularies annually during open enrollment or special enrollment periods.
Comparing Costs and Out of Pocket Exposure
When comparing Medicare B vs D, costs include premiums, deductibles, and sharing for services. Medicare B has a standard national premium, but high income beneficiaries pay more through income related monthly adjust amount adjustments.
Medicare D costs vary widely by plan and drug list, and some plans offer low copays while others have higher premiums but lower coinsurance. Your out of pocket exposure depends on your plan design, the drugs you use, and whether you reach the coverage gap or catastrophic coverage.
Projecting your annual spending for each part helps you decide whether a plan with a slightly higher premium but lower copays saves you money overall.
Enrollment Periods and Eligibility Rules
Most people sign up for Medicare B during their initial enrollment period, which starts three months before your 65th birthday and ends three months after. If you delay Medicare B and do not have creditable coverage, you may face a permanent late enrollment penalty.
Medicare D also has an initial enrollment window when you first become eligible for Medicare. Each plan sets its own annual open enrollment dates, usually in the fall, when you can switch plans or make changes for the following year.
Special enrollment periods may apply if you lose other creditable drug coverage or move out of your current plan service area.
Plan Your Coverage Strategy
- Compare the standard premium and income related adjustments for Medicare B.
- Review each year’s formulary and tiers for any Medicare D plan you consider.
- Check whether your doctors and pharmacies are in network for the plan.
- Project your yearly drug and medical costs to estimate total out of pocket spending.
- Mark important enrollment dates so you do not miss coverage windows or face late penalties.
FAQ
Reader questions
Do I need both Medicare B and a Medicare D plan?
You need Medicare B to have full Medicare coverage, and you should add a Medicare D plan if you take prescription drugs. Without Medicare D, you pay for all retail medications yourself unless you qualify for other assistance.
What happens if I delay signing up for Medicare B or D?
Delaying Medicare B can lead to a permanent penalty added to your premium for as long as you have coverage. Delaying Medicare D without creditable drug coverage also results in a late enrollment penalty based on the time you went without coverage.
Can I change my Medicare D plan each year?
Yes, during the annual election period each fall, you can switch plans, change to a different drug list, or drop coverage. Review your plan’s formulary every year to ensure your medications remain covered at the lowest cost.
How do income related premiums affect Medicare B and D?
If your income exceeds certain thresholds, you pay higher premiums for Medicare B, and those income levels may also affect how much you pay for some Medicare D plans. Your Social Security information usually determines these amounts automatically.