Your Medicare Road Map: What to Know Before You Turn 65

An instructor for my CFP® practitioner exam prep course used to describe Medicare as a piece of Swiss cheese — offering health coverage, but with a lot of holes. And that’s why timing matters so much with Medicare health care planning. Miss the wrong deadline, and those holes can turn into permanent penalties and limited choices. As we dive into the details, let’s start with the most critical piece: the timelines.

Timelines

Initial Medicare enrollment offers a seven-month window: three months before your birth month, your birth month and three months after. For example, if your birthday is in January, you can enroll from October of the prior year through April of the year you turn 65. It is important to enroll during this period because if you miss it, and do not qualify for a special enrollment period, you will be required to pay a higher premium as a penalty for the rest of your life.

There is an annual open enrollment period from October 15 through December 7. During this time, participants may switch between Original Medicare and a Medicare Advantage plan (or vice versa) and may enroll in or change their Part D prescription drug plan. Medicare Advantage participants have an additional open enrollment period from January 1 through March 31, during which they may switch Advantage plans or move back to Original Medicare.

Finally, Medicare supplement plans, often referred to as Medigap, have annual open enrollment, but if participants do not enroll during their initial Medicare enrollment period, they will be subject to medical underwriting and could be denied coverage.

Now let’s figure out what all those plans I mentioned are — and what they do and do not cover.

The ABCs of Original Medicare

Original Medicare is what most people think of when they hear about health care in retirement. It includes Part A, Part B, Part D and usually a supplemental policy.

A common misconception is that once you turn 65, all health-care costs are free. That isn’t true.

Part A covers hospital services. If you’ve worked and paid payroll taxes, Part A is typically free. If not, premiums can exceed $500 per month in 2025. Even then, Part A only covers hospital care — doctor visits, physical therapy and outpatient procedures are not included.

Those services fall under Part B. Part B premiums are income-adjusted based on your Modified Adjusted Gross Income (MAGI) from two years prior. Most people pay $185 per month, but higher-income earners may owe additional Income-Related Monthly Adjustment Amounts (IRMAA) charges, bringing premiums as high as $628.90 per month.

Prescription-drug coverage comes from Part D, with premiums ranging from $0 to $85.80 per month, again based on income. The premium is only part of the story — your total cost depends heavily on the medications you take. Medicare’s online plan finder lets you enter your prescriptions to estimate annual costs and compare options.

One of the largest coverage gaps is Part B coinsurance. Medicare generally covers 80%, leaving you responsible for the remaining 20%, with no out-of-pocket limit. A serious illness could result in substantial uncovered costs.

That’s where Medigap (Medicare supplement) policies come in. These plans are standardized, so coverage is the same regardless of the insurer, though prices vary. Their primary purpose is to cover the Part B coinsurance. Plans C and F are no longer available to new enrollees, and I typically recommend Plan G for its comprehensive coverage. I generally avoid Plans K and L unless other supplemental coverage — such as retiree benefits or TRICARE — is in place.

It’s important to note that Medicare doesn’t offer long-term care coverage. Part A only provides up to 100 days of skilled nursing care. This coverage is limited to post-hospitalization recovery and specifically does not apply to long-term custodial care.

There are a few other small holes worth mentioning. Dental care, vision care and hearing aids are not covered by Original Medicare, which is almost comical given how important and necessary these services are as we age.

Original Vs. Advantage

Enrollees in Medicare have another option to consider: Medicare Advantage. These policies are purchased from a private insurer and are marketed as covering everything — health care, prescriptions, dental care and vision care. However, these plans are built around local networks of doctors and hospitals, so you must be confident you will only ever want to receive care within those networks. If you develop a rare cancer and want treatment at the Cleveland Clinic but live in New Jersey, you are likely out of luck.

You will usually need referrals to see specialists, which you would not need with Original Medicare.

There is a saying that if you never get really sick, Medicare Advantage plans can be great because they are inexpensive. When you do get sick, however, you are limited to a very tight network and must obtain preauthorizations for treatment. In 2023, Medicare Advantage plans processed 50 million preauthorizations, partially or fully denying 3.2 million requests, compared to Original Medicare, which processed only 400,000.

Original Medicare, despite its complexity and cost, offers the most robust medical coverage for retirees.

Medicare decisions don’t happen in a vacuum. Premiums, IRMAA surcharges, prescription drug costs, supplemental coverage and long-term care risks all intersect with taxes, income planning, Social Security timing and overall retirement cash flow. The choices you make at 65 can quietly shape your health-care costs, and your flexibility, for decades.

A CFP® professional helps you look beyond individual Medicare decisions and place them in the context of a holistic retirement plan, weighing trade-offs, anticipating future health and income changes, and avoiding costly mistakes that can’t easily be undone. Medicare may be Swiss cheese, but with the right planning — and the right professional guidance — you can fill the gaps and protect both your health and your retirement security.