Medicare Part A and Part B, Explained Simply

Original Medicare is the traditional form of Medicare, run by the federal government. It has two pieces: Part A, which is hospital insurance, and Part B, which is medical insurance. Together they cover a large share of your health care.

With Original Medicare, you can see any doctor or hospital in the U.S. that accepts Medicare. But it also has real gaps, which is why many people in Los Angeles and Orange County add other coverage on top of it. We explain the gaps below.

Part A is hospital insurance. It helps pay for care you receive as an inpatient, and for certain kinds of follow-up and end-of-life care.

Part B is medical insurance. It covers the everyday, outside-the-hospital side of your care, including services that catch problems early.

Most people pay no monthly premium for Part A. You qualify if you earned 40 quarters of U.S. work credits — roughly 10 years of work. Your spouse's work record can also qualify you, even if you did not work that long yourself.

What if you have a green card but not 40 quarters? Many Korean-American seniors are in this exact situation. After five years of continuous U.S. residency, you can still enroll in Medicare at 65 or older. You pay a monthly premium for Part A, and the amount depends on your work credits and changes each year.

Original Medicare covers a lot, but not everything. Even for covered services, you pay deductibles and a share of many bills, and those amounts change each year. On top of that, some important types of care are not covered at all.

These gaps are why most people add more coverage. A separate Part D plan handles prescription drugs, a Medigap policy helps pay your share of costs under Original Medicare, and a Medicare Advantage plan bundles your coverage a different way. There is no one right answer — it depends on your health, your doctors, and your budget.

Medicare charges a late-enrollment penalty if you delay Part B without qualifying coverage. The penalty is 10% for each full 12-month period you waited, and you keep paying it for as long as you have Part B. That is why timing matters so much.

There is an important exception. If you work past 65 and have group coverage from an employer with 20 or more employees, you can delay Part B without penalty and use a Special Enrollment Period when that coverage ends. COBRA does not count as this kind of coverage, so be careful before you rely on it.

If you missed your window, the General Enrollment Period runs January 1 through March 31 each year, and coverage begins the month after you sign up. If you think you may have missed a deadline, do not wait — call and find out exactly where you stand.