Medicare Part B is medical insurance. It helps pay for medically necessary outpatient services and certain preventive care. Part A is hospital insurance; having Part B alone does not give you all the benefits of both parts.
Examples of Part B services
| Category | What to check |
|---|---|
| Doctor and outpatient visits | Medical necessity, provider participation and the setting of care. |
| Diagnostic tests | Required orders, frequency or condition-specific coverage rules. |
| Preventive services | Eligibility, screening interval and whether the provider accepts assignment. |
| Durable medical equipment | Home-use requirements, an eligible order and an enrolled supplier. |
| Ambulance and mental health services | The particular benefit’s medical and provider requirements. |
Coverage is not automatic just because a provider recommends something. Original Medicare excludes services such as most routine dental care, routine vision exams and long-term custodial care. Review the exact service before relying on payment.
What you pay in 2026
The standard Part B premium is $202.90 per month and the annual deductible is $283. An income-related adjustment or applicable late-enrollment penalty may increase your premium. After the deductible, many covered services leave you responsible for 20% of the Medicare-approved amount when assignment is accepted.
Most covered preventive services have no patient charge when assignment is accepted, but a separate diagnostic service or additional care may have costs. Original Medicare alone has no annual out-of-pocket cap.
Enrollment and start dates
Some people receive Part B automatically; others apply through Social Security or the Railroad Retirement Board as applicable. The usual age-65 Initial Enrollment Period lasts seven months. A birthday on the first of a month shifts that window earlier. Check the actual dates instead of assuming coverage has begun.
If you delay Part B because of qualifying group coverage from current employment, a Special Enrollment Period may apply. It generally ends eight months after the employment or that coverage ends, whichever happens first. COBRA and retiree coverage do not extend that deadline. If no initial or special period applies, the General Enrollment Period is January 1–March 31, with coverage generally beginning the following month; a penalty may apply.
Do not apply the retroactive rules for premium-free Part A to Part B. Confirm the effective date on your official enrollment notice or Medicare card.
Verify your coverage before choosing a plan
- Check whether your Medicare card lists Part B and its start date.
- Confirm whether you receive benefits through Original Medicare or Medicare Advantage.
- Ask about coordination if you also have employer or other insurance.
- Check enrollment rights before delaying, dropping or replacing coverage.
Medicare Advantage requires both A and B. A separate Part D plan requires A or B, while Medigap generally requires both and supplements Original Medicare. These are different coverage decisions.
Start with the Medicare enrollment checklist and review premiums and medical cost sharing before applying.
Related coverage questions
- How to Enroll in Medicare: Steps, Timing and Where to Get Help
- Who Is Eligible for Medicare? Age, Disability and Enrollment
- How to Verify Your Medicare Coverage and Plan Enrollment