Glossary
Medicare Part A
The hospital insurance side of Original Medicare — covers inpatient stays, skilled nursing, hospice, and some home health.
Also known as: Hospital Insurance, Part A
What is it?
Medicare Part A is the hospital insurance component of Original Medicare. It pays for inpatient hospital stays, skilled nursing facility care after a qualifying hospital stay, hospice care, and limited home health care. Most people get Part A premium-free because they (or a spouse) paid Medicare taxes for at least 40 quarters (about 10 years) of work.
Why does it matter?
Part A is the foundation of your Medicare coverage at 65. For retired military, Part A is also a prerequisite for keeping TRICARE benefits — you cannot have TRICARE For Life without Part A and Part B.
When you'll encounter it
You become eligible the first day of the month you turn 65. If you're already collecting Social Security, you're enrolled automatically. Otherwise you actively enroll through SSA during your Initial Enrollment Period (the 7-month window around your 65th birthday).
Impact on Medicare
Part A pays first for covered inpatient services. In 2026 it has a per-benefit-period deductible and daily coinsurance after day 60 of a hospital stay. There is no monthly premium for most people.
Impact on TRICARE For Life
TRICARE For Life acts as the secondary payer behind Part A. TFL typically picks up the Part A deductible and coinsurance for services that are also TRICARE-covered, so most beneficiaries owe $0 out-of-pocket on covered inpatient care.
Impact on Medicare Advantage
If you enroll in a Medicare Advantage plan, the plan administers your Part A benefits using its own copays and network rules instead of Original Medicare's cost shares.
Common misconceptions
- "Part A is automatic for everyone at 65." — Only automatic if you're already receiving Social Security or RRB benefits. Otherwise you must actively enroll.
- "Part A covers long-term custodial nursing home care." — It does not. Part A only covers short-term skilled care after a qualifying hospital stay, up to 100 days per benefit period.
Related lessons
Related glossary terms
Related questions
Official sources
Last reviewed January 2026 against the 2026 Medicare & You and TRICARE For Life handbooks.