Most people turning 65 believe Medicare will take care of their healthcare bills. It covers a lot. But it was never built to cover everything, and that gap is where the most expensive Medicare mistake happens: going with Original Medicare alone, or picking a plan by its monthly premium, without knowing what you would owe if something serious happened.
Here is how the costs really work, what a bad year can look like in dollars, and how to protect yourself before you need to.
Original Medicare Pays a Share, Not the Whole Bill
Original Medicare has two parts that cover your medical care. Each one leaves you with part of the bill.
Part B covers doctors and outpatient care. You pay the Part B deductible first, which is $283 in 2026. After that, Medicare pays 80 percent of the Medicare-approved amount. You pay the other 20 percent. That 20 percent has no yearly limit. It keeps going for as long as you need care.
Part A covers hospital stays. You pay a deductible of $1,736 for each benefit period. A benefit period ends once you have gone 60 days in a row without inpatient hospital or skilled nursing care. That means you can owe this deductible more than once in the same year. If a hospital stay runs past 60 days, you pay $434 per day for days 61 to 90, then $868 per day after that while you use your lifetime reserve days.
Original Medicare also does not include prescription drug coverage. It does not cover most dental care, routine eye exams for glasses, or hearing aids.
What a Bad Year Can Look Like
Say you need outpatient surgery, and the Medicare-approved cost is $10,000. Your 20 percent is $2,000, plus your Part B deductible.
Now say the problem is bigger than one procedure. Chemotherapy given in a clinic is billed under Part B. If a year of treatment adds up to $60,000 in Medicare-approved charges, your 20 percent is $12,000. If you also land in the hospital, add the Part A deductible on top of that.
There is one more cost many people never hear about. Some doctors do not accept Medicare’s approved amount as full payment. They are allowed to charge you up to 15 percent more. These are called excess charges, and Original Medicare does not pay them.
None of this is rare. It is simply how the system is designed. Original Medicare was built to share costs with you, not to cap them.
Three Ways People Make This Medicare Mistake
1. Staying on Original Medicare with nothing behind it
This works fine in a healthy year. In a bad year, there is no ceiling on your share of the bill. Your savings become your backup plan.
2. Choosing a plan by the premium alone
A $0 premium plan is not free. You still pay your Part B premium, and you pay copays and coinsurance when you use care. A plan that costs nothing each month can cost a lot in the month you get sick. The right question is not “What does it cost?” It is “What would it cost me in a bad year?”
3. Waiting too long to look at a Medicare Supplement
When you first enroll in Part B at 65 or older, you get a 6-month window to buy a Medicare Supplement (also called Medigap) without answering health questions. During that window, a company cannot turn you down or charge you more because of your health. After it closes, in most states, the company can ask about your health and say no. Many people find this out years later, after a diagnosis, when it is too late.
Your Two Main Ways to Close the Gap
Medicare Supplement (Medigap) works alongside Original Medicare. It pays some or all of the costs Medicare leaves behind, like the 20 percent and the Part A deductible. You can see any doctor in the country who accepts Medicare. The tradeoff: you pay a higher monthly premium, and you need a separate Part D plan for prescriptions.
Medicare Advantage is offered by private insurance companies approved by Medicare. It has a yearly limit on what you pay out of pocket for covered in-network care. Many plans include drug coverage and some dental, vision, or hearing benefits, though those extras are usually limited. The tradeoff: you pay copays as you go, you use the plan’s network, and some care needs approval first.
Put simply: Medigap costs more each month, but your bills stay small and easy to predict. Medicare Advantage costs less each month, but you pay as you use care, up to the plan’s yearly limit.
If you choose Medicare Advantage, look hard at the hospital copays. Many plans charge a daily copay for the first several days of a hospital stay, and those add up fast. A hospital indemnity plan pays you cash when you are admitted, which can cover those days. These plans ask health questions, so they are easiest to get while you are healthy.
Already on Medicare? Use Open Enrollment as Your Checkpoint
The Annual Enrollment Period runs October 15 to December 7. Plans change every year. Copays, drug lists, and doctor networks can all shift on January 1, even if you change nothing. This is the time to check that your plan still fits your health, your doctors, and your budget.
One caution: you can leave Medicare Advantage for Original Medicare during this period, but buying a Medicare Supplement at that point may mean answering health questions. Know where you stand before you make a switch.
Find Your Gaps Before a Claim Does
The best time to learn what your coverage leaves exposed is before you need it. The Medicare Clarity Score takes about 3 minutes. It checks for penalties, coverage gaps, and overpaying, and it shows you where your risks are. No pressure and no sales pitch.
Prefer to talk it through? Talk with Scott or call 512-844-3983. We work for you, not the insurance companies.
Reviewed by Scott Bowling, licensed Medicare insurance agent in multiple states, TX License #2882146. Last reviewed Last reviewed: October 2026.
We do not offer every plan available in your area. Any information we provide is limited to those plans we do offer in your area. Please contact Medicare.gov or 1-800-MEDICARE to get information on all of your options. Trusted SR Solutions is not connected with or endorsed by the U.S. government or the federal Medicare program.