Medicare Part A covers inpatient hospital care, skilled nursing facilities, hospice, and some home health services. Part B covers outpatient medical care, doctor visits, preventive screenings, and medical equipment. Together, they form what’s known as Original Medicare, and understanding exactly what falls under each part helps you avoid unexpected bills and make the most of your benefits.
What Part A Covers
Part A is hospital insurance. It pays for care you receive as an inpatient, meaning you’ve been formally admitted to a hospital, not just placed under observation. This includes stays at general hospitals, critical access hospitals, and inpatient psychiatric facilities. For 2025, Part A carries a $1,676 deductible per benefit period (not per year). After that, your first 60 days of inpatient care are fully covered. Days 61 through 90 come with a $419 daily coinsurance cost, and if you need to tap into your lifetime reserve days beyond that, the coinsurance jumps to $838 per day.
Part A also covers skilled nursing facility care, but only under specific conditions. You must first have a qualifying inpatient hospital stay of at least three consecutive days. Time spent under observation status does not count toward those three days, which catches many people off guard. You then need to enter the skilled nursing facility within 30 days of leaving the hospital, and the care must be related to the condition that put you in the hospital. Medicare covers the first 20 days in full. Days 21 through 100 require a $209.50 daily coinsurance in 2025. After day 100, Medicare stops covering skilled nursing entirely. If your doctor participates in an Accountable Care Organization or certain other Medicare initiatives, the three-day hospital stay requirement may be waived. Medicare Advantage plans can also waive it.
Hospice care falls under Part A as well. If a doctor certifies a terminal illness with a life expectancy of six months or less and you choose comfort care over curative treatment, Medicare covers hospice services including pain management, counseling, and medical supplies related to the terminal diagnosis.
Home Health Services Under Part A
Part A covers home health care, but only when you meet a specific definition of “homebound.” That means leaving your home requires significant effort, whether because you need a wheelchair, walker, cane, special transportation, or help from another person. It can also mean that leaving home isn’t medically recommended because of your condition.
Even if you qualify as homebound, Medicare only pays for part-time or intermittent skilled services like nursing care or physical therapy. If you need full-time skilled care, home health benefits won’t apply. A healthcare provider must assess you face-to-face before certifying that you need these services, and the care must come from a Medicare-certified home health agency.
What Part B Covers
Part B is medical insurance for outpatient care. It covers two broad categories: medically necessary services (things your doctor orders to diagnose or treat a condition) and preventive services (screenings and shots designed to catch problems early or prevent them altogether).
On the treatment side, Part B pays for doctor visits, outpatient surgeries, lab tests, diagnostic imaging, mental health and substance use disorder treatment, ambulance services, and limited outpatient prescription drugs (most prescriptions fall under Part D instead). It also covers durable medical equipment when ordered by your doctor for use at home. That includes wheelchairs, walkers, hospital beds, oxygen equipment, CPAP machines, glucose monitors with test strips and lancets, crutches, and infusion pumps. To qualify as durable medical equipment, the item must be reusable, medically necessary, primarily useful to someone who is sick or injured, and expected to last at least three years.
The standard Part B premium for 2025 is $185 per month, with an annual deductible of $257. After you meet the deductible, you typically pay 20% of the Medicare-approved amount for most services.
Preventive Services at No Cost
One of Part B’s most valuable features is its lineup of preventive services that cost you nothing out of pocket, as long as you see a provider who accepts Medicare assignment. The list is extensive:
- Cancer screenings: mammograms, colonoscopies, lung cancer screenings with low-dose CT, cervical and vaginal cancer screenings, prostate cancer screenings, colorectal stool DNA tests, and fecal occult blood tests
- Cardiovascular screenings: cholesterol and lipid level tests, plus behavioral therapy for heart disease risk
- Diabetes care: diabetes screenings, self-management training, a full Diabetes Prevention Program, and medical nutrition therapy
- Vaccines: flu shots, COVID-19 vaccines, pneumococcal shots, and hepatitis B shots
- Other screenings: depression, glaucoma, HIV, hepatitis B, hepatitis C, sexually transmitted infections, alcohol misuse, bone density measurements, and abdominal aortic aneurysm
- Wellness visits: a one-time “Welcome to Medicare” preventive visit and a yearly wellness visit to develop or update a personalized prevention plan
Tobacco cessation counseling, obesity behavioral therapy, and HIV pre-exposure prophylaxis (PrEP) are also covered at no cost. These zero-cost preventive benefits only apply when the service is purely preventive. If your doctor discovers a problem during a screening colonoscopy and removes a polyp, for example, you may owe coinsurance for the procedure portion.
What Original Medicare Does Not Cover
The gaps in Parts A and B are significant, and they surprise many people. Original Medicare does not cover:
- Dental care: routine cleanings, fillings, tooth extractions, and dentures
- Vision: eye exams for prescription glasses and the glasses themselves
- Hearing: hearing aids and the exams to fit them
- Long-term care: custodial care in a nursing home when you don’t need skilled medical services
- Cosmetic surgery
- Massage therapy
- Routine physical exams (the yearly wellness visit is covered, but a traditional head-to-toe physical is not the same thing)
Many people fill these gaps through Medicare Advantage plans (Part C), standalone dental and vision plans, or Medigap supplemental insurance policies.
Enrollment and Timing
Your initial enrollment period is a seven-month window: it starts three months before the month you turn 65, includes your birthday month, and ends three months after. If you’re already receiving Social Security or Railroad Retirement Board benefits at least four months before turning 65, you’ll be automatically enrolled in both Part A and Part B. If you’re not receiving those benefits, you need to contact the Social Security Administration and sign up yourself.
People under 65 who qualify through disability are automatically enrolled in Part A after 24 months of receiving disability benefits. Most people pay no premium for Part A because they or a spouse paid Medicare taxes for at least 40 quarters (10 years) of work. If you have 30 to 39 quarters, the reduced Part A premium is $285 per month in 2025. Fewer than 30 quarters means you’d pay the full $518 per month.
Late Enrollment Penalties
If you miss your initial enrollment window and don’t qualify for a special enrollment period (typically through employer coverage), Part B carries a permanent penalty. Your premium increases by 10% for every full 12-month period you were eligible but didn’t sign up. Someone who waited two years past their window, for instance, would pay a 20% surcharge on top of the standard premium for as long as they have Part B. For 2026, that standard premium is $202.90 per month, so a 20% penalty would add roughly $40.58 every month, indefinitely. That penalty never goes away, which makes understanding your enrollment timeline one of the most financially important parts of Medicare planning.