Medicare billing errors — how to read and dispute medical bills
Reviewed by the How To Help Your Elders Team | Updated March 2026
Medicare billing errors are common, fixable, and worth catching. Charges get duplicated, preventive services get billed incorrectly, and procedure codes get entered wrong. Your parent has 120 days from the date on the Explanation of Benefits to request a Medicare review, and the appeal process is free.
Billing Mistakes Happen Regularly, and You Have the Right to Challenge Them
Your father received an Explanation of Benefits in the mail that made no sense. Medicare approved a charge of $500 for a procedure that was supposed to be preventive and therefore free. Or you see a bill with the same charge appearing twice. Or your dad had lab work that seemed routine, but the bill shows three separate charges for what seemed like one test. You stare at the paperwork, trying to figure out if someone made a mistake or if this is just how Medicare billing works.
The frustration is real, and you're not being paranoid by thinking something might be wrong. According to CMS, Medicare processes over one billion claims per year. With that volume, errors happen regularly. Charges get duplicated. Services that should be free are billed as if they cost money. Procedures get coded incorrectly, so Medicare pays less than it should or the provider bills your parent for more than they owe.
The process of fixing errors isn't quick or automatic. It requires some persistence and willingness to ask questions. But the money saved is often worth the effort, especially if the mistake is a significant charge. You're not being difficult by questioning a bill. You're being a responsible family member protecting your parent's finances.
Reading the Explanation of Benefits
Medicare sends an Explanation of Benefits for every claim it processes. The EOB is dense, full of codes and abbreviations, and not designed to be easy to understand. It's also the single most important document for understanding what Medicare approved, what it paid, and what your parent owes.
At the top of the EOB is your parent's name, Medicare number, and the date the EOB was created. The next section lists the provider who submitted the claim, whether that's a doctor's office, hospital, lab, or imaging center. The claim number appears here, and you'll need it if you dispute the charge.
The actual claim details come next, and this is where you find the critical information. The line item shows the service code, the date the service was provided, a description of the service, the amount the provider charged, the amount Medicare approved, what Medicare paid, and what your parent owes. This line-by-line breakdown is where errors become visible.
The provider charged amount is what the doctor's office billed Medicare. This isn't what your parent pays. Medicare's approved amount is what Medicare decided is a reasonable charge for that service, and it's usually less than what the provider charged because Medicare negotiates rates. What Medicare paid is typically 80 percent of the approved amount if your parent has Original Medicare. Your parent's responsibility is the difference between what Medicare approved and what Medicare paid, which is the copay or coinsurance.
At the bottom of the EOB, it shows how much your parent owes the provider. If it says zero, your parent owes nothing. If it says fifty dollars, your parent owes fifty dollars, not the provider's original charge of three hundred. This is the basic structure of every EOB, and once you understand the sections, you can use them to spot errors.
Common Billing Errors to Look For
Duplicate charges are the most obvious error to spot. If your parent had one lab test, there should be one charge for that test. If the EOB shows the same test code twice with the same date of service and the same charged amount, that's a duplicate. Duplicates happen because office staff enter the claim twice, or because a claim gets resubmitted and both the original and resubmitted claim get processed.
Charges for services your parent didn't receive are another category. If the EOB shows a charge for a procedure your parent is certain they didn't have, that's a mistake. This sometimes happens when a provider charges for an office visit every time your parent calls or when they charge for tests they ordered but never performed. Sometimes it's a coding error. Rarely, it's intentional fraud, but more often it's an honest mistake.
Charges for preventive services that should be free are common. Medicare covers certain preventive services at no cost if the service is performed as preventive care. According to Medicare.gov, covered preventive services include the annual wellness visit, certain cancer screenings, cardiovascular screenings, and vaccinations, all at zero cost to the beneficiary. If your parent had blood work as part of an annual wellness visit, that should be free. If the same blood work was ordered because of a specific symptom, it might be billed as diagnostic rather than preventive, which means there's a copay. But if the service was preventive, it shouldn't have a charge.
Dates of service that don't match when your parent actually received care are a red flag. If the EOB shows a service on a date when your parent wasn't seen, that's an error. It might be a data entry mistake or it might mean the charge was for a different patient. The date matters because billing windows have deadlines, and if the date is wrong, the appeal timeline might be wrong too.
Charges appearing with the wrong provider name suggest a claim got routed to the wrong place. If your parent saw Dr. Smith but the charge says it's from Dr. Jones, that's a mismatch that needs correction.
The Difference Between EOB and Patient Bill
This is where people get confused, so the distinction matters. The EOB is what Medicare sends to you and your parent. It tells you what Medicare approved and paid. The patient bill is what the provider sends. It tells you what you owe.
These don't always match. An error on the EOB doesn't mean the patient bill is wrong, and an error on the patient bill doesn't necessarily mean the EOB is wrong.
Here's how they can disagree. Medicare sends the EOB showing that your parent owes fifty dollars in coinsurance. But the provider's bill shows a hundred dollars. This disagreement might exist because the provider is trying to collect something Medicare says is the provider's responsibility, because the provider hasn't processed the Medicare payment yet, or because the provider coded the claim differently than Medicare coded it.
The correct answer comes from the EOB, not the patient bill. Medicare.gov states that your parent's responsibility is what the EOB says it is. If the patient bill disagrees, your parent should contact the provider and explain what Medicare's EOB shows. If the provider continues to bill incorrectly, that's a separate issue to take up with your state's insurance commissioner.
How to Challenge a Charge You Believe Is Wrong
Start by asking the provider for clarification. Call the billing department at the office where your parent received care and say something like, "I received an EOB showing two charges for the same lab test on the same date. Can you explain why this charge appears twice?" The billing staff person might check their records and discover immediately that it was an error and resubmit a corrected claim. Many errors get resolved at this step.
If the provider says they don't see any error, ask for an itemized bill. An itemized bill breaks down every charge separately and explains what each charge is for. A simple bill might say "Office Visit" for fifty dollars. An itemized bill says "Office Visit: Preventive Care" or "Office Visit: Sick Visit." The itemized bill helps you understand whether the charges match what you expected.
If the itemized bill still doesn't make sense and the provider won't acknowledge an error, you can submit a formal written request to the provider asking them to review the bill. Explain what you believe is wrong and ask for a formal review. The provider's compliance officer or medical records department handles this kind of request.
If the provider's review comes back and they still maintain the charge is correct but you disagree, you can file an appeal with Medicare. You have 120 days from the date on the EOB to request that Medicare review the claim. To appeal, submit a form explaining why you believe the charge is wrong and what evidence supports your position. Attaching a copy of the EOB, your request to the provider, and the provider's response helps Medicare understand the dispute.
Medicare's appeal process is free. If Medicare's initial review supports your position, they work with the provider to reduce or remove the charge. If Medicare doesn't support you, you can appeal to a Medicare Administrative Law Judge. This takes longer and requires more documentation, but it's available if you believe Medicare made an error.
Protecting Yourself from Future Billing Problems
Keep your own record of appointments and procedures. After each visit, write down the date, the provider, what was discussed, what tests or procedures were ordered, and what the provider said the cost would be. If the provider said something is preventive and free, note that. This record is your reference point for checking against the EOB later.
Ask for itemized bills from providers, not just statements showing a total. Before leaving an appointment, ask whether there will be any charges, what the charges are for, and whether insurance will cover them. If the provider says there won't be a charge, ask them to note that in the record.
When you receive an EOB, spend ten minutes reading it and comparing it to what you expected. If the charged amount doesn't match what the provider said, that's worth investigating. If a charge appears for a service you don't remember, that's worth investigating. Catching errors early gives you more options for fixing them.
Catch errors within 120 days of the EOB date if possible. After 120 days, Medicare's appeal timeline has passed and your options are limited. Some providers also have their own time limits for billing disputes, often shorter than Medicare's 120-day window.
When to Get Help: Billing Advocates and SHIP
SHIP counselors can help you dispute bills and understand billing issues. Every state's SHIP program has trained counselors who know how to read EOBs, know where the common errors happen, and can advocate with providers on your behalf. SHIP is free and federally funded.
Some nonprofits specialize specifically in billing error correction. They might charge a fee if they recover money, but many will review a disputed bill free of charge. If a significant amount of money is at stake, these advocates can be worth the cost.
An attorney makes sense only if the disputed amount is large enough that the attorney's fees would be justified by the potential recovery. If the error is fifty dollars and an attorney charges two hundred dollars per hour, it doesn't make financial sense. If the error is five thousand dollars, an attorney might be worth considering.
Medicare billing is complicated, and errors happen. The system isn't designed to be easy for patients to understand. But errors are correctable. When you find a billing mistake, you have the right and the ability to challenge it. It takes time and persistence, but the money saved is real. Every error you catch and correct protects your parent's financial security and makes the system a little cleaner for everyone.
Frequently Asked Questions
How long do I have to dispute a Medicare billing error?
You have 120 days from the date on the Explanation of Benefits to file an appeal with Medicare. Contacting the provider directly can happen anytime, but the formal Medicare appeal process has this deadline. Starting early gives you more time to gather documentation.
What's the difference between an EOB and a bill?
The EOB (Explanation of Benefits) comes from Medicare and shows what Medicare approved and paid. The bill comes from the provider and shows what your parent owes. If the two disagree, the EOB is the authoritative document. Your parent's responsibility is what the EOB says it is.
Does it cost anything to appeal a Medicare billing error?
No. The Medicare appeals process is completely free. You can file an appeal without paying any fees, and if Medicare finds in your favor, the charge is corrected at no cost to you.
What if the provider keeps sending bills for a charge I'm disputing?
While a dispute or appeal is in process, the provider may continue sending bills. Send the provider a written notice that the charge is being disputed and include your appeal confirmation number if you've filed with Medicare. Most providers will pause collection efforts while a formal dispute is pending.
Can a SHIP counselor help me read my EOB?
Yes. SHIP counselors are trained specifically to help Medicare beneficiaries understand their EOBs, identify billing errors, and file disputes. The service is free. Find your state's SHIP program at shiphelp.org or call 1-877-839-2675.
What counts as a "billing error" versus just a confusing bill?
A billing error is any charge that is incorrect: duplicate charges, charges for services not received, incorrect dates of service, wrong provider listed, or preventive services billed with a copay when they should be free. A confusing bill might be accurate but hard to understand. In both cases, calling the provider's billing department for clarification is the right first step.