Medicare Explained: What to Know Before You Turn 65

Turning 65 comes with an important financial milestone: Medicare eligibility. I’ve seen many people assume Medicare is automatic and fully covers healthcare, only to be surprised by enrollment rules, premiums, and coverage gaps. Understanding how Medicare works before you enroll can prevent costly mistakes and lifelong penalties. Here’s a practical breakdown to help you make informed decisions.

Qualifying for Medicare
To qualify for Medicare, you must be a U.S. citizen or legal permanent resident for at least five continuous years and be age 65 or older. You also generally need 40 quarters (10 years) of Medicare-taxed work. If you don’t have enough quarters, you may qualify through a spouse or even an ex-spouse if the marriage lasted at least 10 years and you meet eligibility rules. This is more common than many realize, especially for spouses who spent years out of the workforce.

Understanding Medicare Parts and Costs
Medicare is divided into parts, and each part serves a different role. Original Medicare includes Part A and Part B. Part A covers inpatient hospital stays, skilled nursing, home health, and hospice. For most people with sufficient work history, Part A has no monthly premium. Part B covers outpatient care, doctor visits, labs, preventive care, and durable medical equipment. The standard Part B premium is $202.90 per month in 2026, with higher premiums for higher-income beneficiaries due to IRMAA adjustments. Importantly, Part B typically covers about 80% of approved services, leaving you responsible for the remaining 20% unless you have supplemental coverage.

Enrollment Periods Matter
Timing your enrollment is critical. Your Initial Enrollment Period (IEP) is a 7-month window: three months before your 65th birthday month, your birthday month, and three months after. If you or your spouse are still working and covered by a qualifying employer plan, you may delay Part B and use a Special Enrollment Period later. Missing enrollment without credible coverage can trigger a late penalty of 10% per year of delay — and that penalty usually lasts for life.

Medicare Advantage vs. Medigap
Once enrolled in Parts A and B, you must choose how to fill coverage gaps. That’s where Medicare Advantage and Medigap come in. Medigap (supplemental insurance) works alongside Original Medicare and helps pay deductibles and coinsurance. These plans have monthly premiums but offer predictable costs and broad provider access. Plan G and Plan N are among the most popular choices. For example, Plan G requires you to pay the Part B deductible ($283 in 2026) and then typically covers most remaining approved costs.

Medicare Advantage (Part C) replaces Original Medicare with a private plan. Many Advantage plans have low or even $0 premiums and include drug coverage plus extras like dental or vision. The tradeoff is network restrictions, co-pays, and annual maximum out-of-pocket limits that can reach several thousand dollars. Advantage plans operate more like managed care and may require referrals or prior authorizations.

Why Medigap Open Enrollment Is Crucial
Your Medigap Open Enrollment Period lasts six months starting when you enroll in Part B at age 65 or older. During this time, you can buy any Medigap plan available in your area without medical underwriting. After this window, you may be denied or charged more due to health conditions unless your state has special rules. This window is one of the most important Medicare deadlines to understand.

Referrals and Authorizations
With Medigap, you generally don’t need referrals or prior authorizations. If a provider accepts Medicare, they accept your supplement. Advantage plans often require referrals and prior approvals for certain services. This doesn’t make them bad plans — but it does mean more managed oversight.

Plan Stability
Medigap plans are standardized and remain consistent year to year, although premiums can change. Advantage plans can change benefits, networks, co-pays, and drug formularies annually. That means Advantage enrollees should review plans each year during Open Enrollment.

Perks vs. Predictability
Advantage plans often include extras like dental, vision, hearing, and gym memberships. Medigap plans typically don’t bundle these perks, though some carriers offer minor extras. The decision often comes down to whether you value predictable healthcare costs and provider flexibility or lower premiums with managed networks and added benefits.

Switching and Qualification Rules
You can switch Advantage plans during annual enrollment without medical underwriting. Changing Medigap plans later may require underwriting unless you live in a state with birthday or anniversary rules that allow easier switching. Knowing your state’s rules matters.

Access to Major Clinics
Top-tier medical centers such as Mayo Clinic and Cleveland Clinic widely accept Original Medicare with supplements. Some do not accept certain Advantage plans, depending on contracts and networks. This can matter if you want access to specialty care across the country.

Choosing What Fits Your Life
There’s no universal “best” plan. Medigap often fits people who want predictable costs, nationwide access, and minimal referrals. Advantage may suit those on tighter budgets who are comfortable with networks and value bundled perks. Frequent travelers often prefer Medigap for its flexibility.

The Bottom Line
Medicare is not one-size-fits-all. The decisions you make at 65 can affect your healthcare costs and access for years. Taking time to understand enrollment timing, coverage options, and plan structures can save thousands and reduce stress later.