Medical Billing Errors: The 80% Problem and How to Fight Back

Up to 80% of hospital bills contain at least one error. If your bill looks too high, it probably is. Errors range from small typos to thousands of dollars in fake charges. You have the right to fight every one of them. Here is how.

The 80% Problem Is Real

That 80% figure gets shared a lot. But what does it mean?

Billing auditors and patient advocates find errors on 49% to 80% of hospital bills. The range depends on the type of bill. But the direction is always the same: errors are normal, not rare.

The federal government backs this up. CMS found $31.7 billion in wrong Medicare payments in 2024 alone. A CMS audit also found coding errors on 44% of internal medicine visits.

Pat Palmer has been checking medical bills for 30 years. She is a patient advocate and author of The Medical Bill Survivor Guide. She says she finds errors on about 9 out of 10 hospital bills she reviews. Some of the worst cases: an Illinois hospital charged one patient $186,000 for 200 heart valves. Another family was billed for a circumcision of their baby girl.

Those are extreme cases. But smaller errors happen all the time. A $300 charge for a service you never got. A lab test billed twice. A visit coded at a higher level than it really was. It adds up fast.

Why Medical Bills Are So Hard to Read

There are nearly 70,000 diagnosis codes in the U.S. billing system. There are also over 71,000 procedure codes. Hospitals hire whole departments just to handle the complexity.

You get a summary bill. It shows a total and tells you what you owe. It does not list the individual charges that make up that total. That is not an accident. The harder a bill is to read, the less likely you are to check it.

One hospital visit also creates multiple bills. Your surgeon bills you. So does the anesthesiologist. The radiologist who read your scan sends a separate invoice. The ER doctor may work for a different company than the hospital. Each one can make its own errors. Nobody inside the system is checking for you.

A 2024 study found 1 in 5 Americans got a medical bill they disagreed with last year. That number is probably low.

The Most Common Medical Billing Errors

Knowing what to look for makes the review much faster. Here are the errors that show up most often.

Upcoding

This is when a provider bills for a higher level of care than what actually happened. A routine follow-up visit gets coded as a Level 5 (the most complex and expensive). A Level 5 ER visit can cost $1,000 more than a Level 3. You got a Level 3. They billed you for a Level 5.

Duplicate Charges

The same service billed twice. This happens a lot with lab work, medications, and supplies. A blood draw billed at admission and again at discharge. You will only catch duplicates if you read the line items.

Unbundling

Some procedures must be grouped under one billing code. Unbundling means charging for each part separately, which raises the total. When it is done on purpose, it is fraud. When it is an accident, it still costs you money.

Phantom Services

Billed for something that never happened. A drug you refused. A therapy session you canceled. A follow-up call that was never made. One of the most common phantom charges: room and board fees for days after you left the hospital.

Balance Billing Violations

The No Surprises Act took effect in January 2022. It says out-of-network providers at in-network hospitals cannot charge more than your in-network rate. Emergency doctors, anesthesiologists, and radiologists are the most common sources of these surprise bills. If you got one, it may be illegal.

Wrong Codes and Data Entry Errors

A wrong digit in a code can flip a $200 charge to a $2,000 one. A wrong date can cause your insurance to deny the claim. Then the full bill comes to you. These look like small mistakes. They still cost real money.

How to Get an Itemized Bill

The summary bill does not show individual charges. You need the itemized bill. This lists every charge by service, date, and code. It is the only way to check your bill for errors.

Call the billing department. Ask for an itemized statement of all charges. Ask them to include the CPT (Current Procedural Terminology) codes next to each line item. Write down who you talked to and the date.

Most hospitals will not send this to you unless you ask. If they push back, say you need it before making payment. They are required to provide it.

Also get your Explanation of Benefits (EOB) from your insurance company. The EOB shows what your insurer was billed, what was approved, and what you are supposed to owe. Compare it to the itemized bill line by line. Any gap between the two is worth questioning.

How to Fight Medical Billing Errors: Step by Step

Once you spot something wrong, follow these steps.

1. Write it down first. Note the line item, the code, the date, and the amount. Do this before you call anyone. If the dispute gets heated, your written notes protect you.

2. Call the billing department. Be calm and specific. "I was billed for a Level 5 visit on March 14. It was a routine follow-up. The correct code should be Level 2 or Level 3. Can you review this?" Keep notes: who you spoke with, what they said, and any reference number.

3. Get corrections in writing. If they agree there was an error, do not pay until you have the new amount in writing.

4. Check the hospital's posted prices. Since 2021, federal law requires hospitals to post their prices online. This is the Hospital Price Transparency Rule. If the hospital charged you more than its own posted price, that is a potential federal violation. You can use this in your dispute.

5. File a formal billing error dispute in writing. If the phone call goes nowhere, send a written letter. Include your EOB and any price transparency data you found. Keep copies of everything you send and receive.

For the full process from start to finish, see our step-by-step medical bill dispute guide.

Keep a Paper Trail the Whole Way

This is the step most people skip. It hurts them later.

Every time you contact the billing department, write down the date, the name of the person, what they said, and any reference number. Do not trust your memory. If this goes to a demand letter or small claims court, your notes are your case.

Save every bill, every EOB, and every letter. Take photos of paper mail as backup. Make a folder just for this dispute. The more organized you are, the faster it resolves.

When the Hospital Says the Bill Is Correct

This is where most people give up. They call. They dispute. The hospital says the bill is right. They feel stuck.

But they are not.

A demand letter is the next move. It states the error, cites your proof, and demands a fix within a set time. Your EOB, the hospital's price data, or the No Surprises Act can all serve as proof.

Phone calls get ignored. Demand letters do not. They create a legal record. They signal you are ready to escalate. That shift in tone changes outcomes.

PettyLawsuit sends these letters for you. You describe the dispute. The letter goes out the same day. If the hospital does not respond, follow-up calls are made. A Final Notice goes out on day 10. Over 70% of disputes resolve without going to court. PettyLawsuit has helped more than 2,500 people resolve billing disputes this way.

If it still does not resolve, small claims court is the next step. Hospital billing departments do not want to appear in court. The cost of sending a lawyer often tops the disputed amount. That math works in your favor.

For more on what to do after a denial, see our post: Hospital Denied Your Medical Bill Dispute? Here's What to Do Next.

Ready to act now? Start here: Medical Bill Dispute.

Frequently Asked Questions

What percentage of medical bills have errors?

Billing auditors report that 49% to 80% of hospital bills have at least one error. CMS found $31.7 billion in wrong Medicare payments in 2024. A CMS audit found coding errors on 44% of internal medicine visits.

What are the most common medical billing errors?

The most common errors are upcoding (charging for a higher level of care), duplicate charges (billing the same service twice), phantom services (charges for things that never happened), unbundling (splitting procedures to inflate the total), and illegal surprise bills under the No Surprises Act.

How do I get an itemized hospital bill?

Call the billing department and ask for an itemized statement with CPT codes. You have the right to request it before paying. Compare it to your EOB from your insurance company. Any gap is worth disputing.

What if the hospital refuses to fix the billing error?

File a formal written dispute with your EOB as proof. If that gets ignored, send a demand letter. A demand letter creates a legal record and changes the tone of the dispute. If the hospital still does not respond, small claims court is a real option for most billing disputes.

What is upcoding?

Upcoding means billing for a higher level of care than what actually happened. A basic office visit gets coded as a complex Level 5 visit. The price difference between codes can be hundreds of dollars. It is the most common type of billing overcharge.

Can I dispute a medical bill in collections?

Yes. Under the FDCPA, you can ask the collector to prove the debt is real. You have 30 days from first contact to do this. If the original bill had errors, you can still dispute them. You can also file a complaint with the CFPB if the collection is wrong.