Medicare Explained: Parts A, B, C, D, and Medigap

Medicare is the federal health insurance program serving 67.9 million Americans as of 2024, including people 65 and older, certain younger adults with disabilities, and those with End-Stage Renal Disease. (Source: CMS, 2024)

Part A — Hospital Insurance

Part A covers inpatient hospital stays, skilled nursing facility care, hospice services, and some home health care. Most people pay $0 in premiums.

• 2026 inpatient deductible: $1,736 per benefit period
• Days 1–60: $0 coinsurance after deductible
• Days 61–90: $434/day coinsurance

(Source: CMS, 2026)

Part B — Medical Insurance

Part B covers physician services, outpatient care, lab tests, durable medical equipment, and preventive services.

• 2026 standard monthly premium: $202.90
• Annual deductible: $283
• After deductible: you typically pay 20% of approved costs
• Higher-income beneficiaries pay more via IRMAA

(Source: CMS, 2026)

Part C — Medicare Advantage

Medicare Advantage plans are offered by private insurers approved by Medicare. Each plan must cover everything Original Medicare covers, and most bundle Part D.

• 54% of beneficiaries chose Medicare Advantage in 2025 (Source: KFF)
• Many plans include dental, vision, hearing, and fitness benefits
• Networks are typically HMO or PPO
• Plan availability and costs vary by county

Part D — Prescription Drug Coverage

Part D helps cover prescription medications. Available standalone or bundled in Medicare Advantage.

• 2026 national base premium: $38.99/month
• Plans vary in formularies, tiers, and copays
• Late enrollment penalty applies if you go 63+ days without creditable drug coverage

(Source: CMS, 2026)

Medigap (Medicare Supplement)

Medigap policies fill the cost-sharing gaps in Original Medicare — deductibles, copayments, and coinsurance.

• Best enrollment: 6-month Medigap Open Enrollment starting at age 65 with Part B
• During this window, insurers cannot deny coverage based on health
• Cannot be used alongside Medicare Advantage

Enrollment Periods

• Initial Enrollment Period (IEP): 7 months around your 65th birthday
• Annual Enrollment Period (AEP): October 15 – December 7 each year
• General Enrollment Period (GEP): January 1 – March 31
• Special Enrollment Period (SEP): Triggered by qualifying life events

Penalty warning: Missing your IEP results in a permanent 10% surcharge per year added to your Part B premium. (Source: Medicare.gov)

Who Is Eligible

• Age 65+ — U.S. citizen or permanent resident for 5+ years
• Under 65 with disability — after 24 months on SSDI
• ALS — Medicare begins immediately with SSDI, no waiting period
• End-Stage Renal Disease — eligible regardless of age