Medicare 101

Medicare can feel like alphabet soup—Parts A, B, C, D—and the rules change depending on how you enroll. This quick guide explains what each part covers, what it doesn’t, when to sign up, and how to avoid the gotchas that cost people money every year.

The Four Parts, Plain and Simple

Think of Original Medicare as the core (Parts A and B). You can keep it “as is” and pair it with a Medigap plan for predictability—or you can choose a Medicare Advantage plan (Part C) that replaces A and B with a private plan. Part D handles prescriptions either way.

Part A — Hospital

Inpatient hospital care, limited skilled nursing facility (short-term rehab after a qualifying hospital stay), some home health (skilled/intermittent), and hospice. Most people pay no monthly premium for Part A, but there’s a deductible per “benefit period.”

Part B — Medical

Doctor visits, outpatient care, labs, imaging, durable medical equipment, many preventive services. Part B has a monthly premium, a small annual deductible, and typically 20% coinsurance—and Original Medicare has no out-of-pocket maximum, which is why many people add a Medigap plan.

Part C — Medicare Advantage

Private plans that bundle Part A and Part B (and often Part D). They add an annual out-of-pocket maximum and extras (dental/vision in some cases), but use networks and prior authorizations. You still pay your Part B premium; some plans have an additional premium.

Part D — Drug Coverage

Prescription coverage via a stand-alone plan (if you’re on Original Medicare) or built into many Advantage plans. Costs depend on the plan’s formulary and pharmacy network. If you go too long without “creditable” drug coverage, late penalties can apply.

What Medicare Doesn’t Cover (Common Surprise)

Medicare is designed for medical care. It does not pay for long-term, day-to-day “custodial” care (help with bathing, dressing, eating). It does cover short-term skilled rehab after a qualifying hospital stay, generally up to 100 days per benefit period, with cost-sharing after day 20.

Enrollment Windows (Don’t Miss These)

Sign-up timing affects your costs and coverage start dates. Here are the key windows, in plain English:

• Initial Enrollment Period (IEP): The 7-month window around your 65th birthday (3 months before, the month of, and 3 months after). This is the cleanest time to enroll in Parts A and B.
• Special Enrollment Period (SEP): If you’re covered by active employer group health insurance (yours or your spouse’s), you can delay Part B and enroll later without penalty. When that coverage ends, you typically get an 8-month SEP.
• General Enrollment Period (GEP): If you missed your IEP/SEP, you can enroll Jan 1–Mar 31; coverage generally starts the first of the month after you enroll.

Medigap timing matters: Your best shot at any Medigap plan at standard rates is the first 6 months after your Part B starts (no health underwriting in most states during that window).

Original Medicare + Medigap vs. Advantage (How to Choose)

There’s no one “right” path—just the one that fits how you get care.

• Original Medicare + Medigap + Part D: Broad access to providers nationwide; predictable costs; higher monthly premiums; separate drug plan.
• Medicare Advantage (Part C): Lower monthly premiums; built-in extras; network rules and prior authorizations; you’ll use the plan’s doctors/hospitals and have an annual out-of-pocket maximum.

Costs & Penalties (Avoid the Gotchas)

Three items trip people up the most—worth a minute to check now:

• IRMAA: Higher-income retirees may pay a surcharge on Part B and Part D based on tax returns from two years ago. Appeals are possible after certain “life-changing events.”
• Part B late penalty: If you go 12+ months without Part B when you should have had it (and no employer SEP applies), your premium can increase permanently.
• Part D late penalty: If you go 63+ days without creditable drug coverage, a small % penalty is added to your Part D premium—permanently.

Action Steps (Next 30–60 Minutes)

• Decide your path: Original + Medigap + Part D or Medicare Advantage.
• If choosing Medigap, note your 6-month Medigap window starting from your Part B effective date.
• Check for IRMAA by looking at two-years-ago income; consider whether an appeal might apply.
• Verify you won’t trigger Part B/D penalties (don’t go bare without creditable coverage).

Related Reading on Senior Town Hall

• Long-Term Care: Understanding the Costs & Coverage Options
• Estate Planning: Dignity, Control, and Protecting Loved Ones
• Figure the Figures – How Much Money Do You Need to Retire?

Disclaimer: This article is for educational purposes only and not legal, tax, or medical advice. Medicare rules and plan details vary; confirm specifics with Medicare and plan providers.