Medicare in Plain Language: A Guide to Your Options and When to Enroll

Medicare is one of the most important insurance decisions you'll make — and one of the most confusing. Parts A through D, Medigap, Medicare Advantage, enrollment windows, and penalties: here's what you actually need to know.

The Basics: Parts A and B

"Original Medicare" consists of two parts:

• Part A (Hospital Insurance) — Covers inpatient hospital stays, skilled nursing facility care, hospice, and some home health. Most people pay no monthly premium for Part A if they or their spouse worked and paid Medicare taxes for at least 10 years.
• Part B (Medical Insurance) — Covers doctor visits, outpatient care, preventive services, and medical equipment. Part B has a monthly premium (around $202.90/month in 2026 for most people, though higher earners pay more) and an annual deductible.

Original Medicare covers roughly 80% of approved medical costs after your deductible. You're responsible for the remaining 20% — with no out-of-pocket maximum. That's the gap that Medigap and Medicare Advantage are designed to address.

Part D: Prescription Drug Coverage

Part D covers prescription drugs and is sold through private insurance companies. If you have Original Medicare, you'll want to add a standalone Part D plan unless you have other creditable drug coverage. Plans vary significantly — different drugs, different formularies, different costs.

Skipping Part D when you first become eligible can result in a permanent late enrollment penalty added to your premium later.

Medicare Advantage vs. Medigap: The Key Difference

This is the decision most people find confusing. Here's the clearest way to think about it:

Medicare Advantage (Part C) replaces Original Medicare. You get your coverage through a private insurance company, which typically bundles Parts A, B, and often D into one plan. Many Advantage plans charge $0 monthly premium and include extra benefits like dental, vision, and hearing. The tradeoff: you're in a managed care network (HMO or PPO), and out-of-pocket costs for serious illness can be higher.

Medigap (Medicare Supplement) works alongside Original Medicare — it doesn't replace it. A Medigap policy pays some or all of the cost-sharing that Original Medicare leaves behind (coinsurance, copays, deductibles). You can see any doctor or specialist who accepts Medicare, anywhere in the country. Medigap plans have a monthly premium in addition to your Part B premium, but your out-of-pocket costs for care are highly predictable.

The right choice depends on your health, your preferred doctors, your budget, and how much predictability you want.

When to Enroll: The Enrollment Windows

Getting the timing right matters. Here are the key windows:

• Initial Enrollment Period (IEP) — A 7-month window that starts 3 months before your 65th birthday month, includes your birthday month, and ends 3 months after. This is your first opportunity to enroll in Medicare.
• General Enrollment Period (GEP) — January 1 through March 31 each year, for people who missed their IEP. Coverage starts the first of the month after you enroll, and you may owe a late enrollment penalty.
• Annual Enrollment Period (AEP) — October 15 through December 7. This is when anyone on Medicare can switch plans, including moving between Medicare Advantage and Original Medicare. Changes take effect January 1.

If you're still working at 65 and covered by a qualifying employer plan, you may be able to delay Medicare enrollment without penalty. The rules here are specific and depend on your employer's size — it's worth talking through your situation before making any decisions.

The Late Enrollment Penalty

If you don't enroll in Part B when you're first eligible and don't have other qualifying coverage, you'll pay a permanent 10% penalty for every 12-month period you delayed. That penalty stays with you for as long as you have Part B. The same applies to Part D — a 1% penalty per month of delayed enrollment.

Getting Help Navigating the Options

The right Medicare plan depends on your specific doctors, prescriptions, and budget. Medigap Plan G from one carrier covers exactly the same things as Plan G from another carrier — but prices vary. Medicare Advantage plans differ by network, benefits, and out-of-pocket limits. Comparing them side by side makes a real difference.

We help Medicare-eligible clients compare options at no cost. Our compensation comes from the carrier if you enroll — there's no charge to you for the help.