How to Spot Medical Billing Errors

And what to do if you find one

Michelle Crouch,

AARP

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En español

Published May 30, 2025

Here's how to identify potentially costly mistakes in medical bills, and what you can do to fix them.

Photo Collage: AARP; (Source: Getty Images (3))

In 30 years of analyzing medical bills for errors, Pat Palmer has seen some jaw-dropping mistakes: Medications and devices marked up 100 percent to 300 percent; a Illinois hospital that charged a man $186,000 for 200 heart valves; a bill sent to new parents for a circumcision — of their baby girl.

Palmer, a patient advocate and author of The Medical Bill Survivor Guide, estimates that she finds an error on about 9 out of every 10 hospital bills she examines and about 7 of every 10 physician bills.

“Whether they are intentional or unintentional, that’s money out of everybody’s pocket,” says Palmer, co-founder of MedCost Solutions, a health benefits solutions company.

According to a survey published in JAMA Health Forum in August 2024, about 1 in 5 people said they received a medical bill over the past year that they disagreed with or couldn’t afford.

Older adults are especially vulnerable to billing errors. With more chronic conditions and more frequent and complex medical care, they face a greater chance of incorrect charges, according to the Consumer Financial Protection Bureau (CFPB).

Even though nearly all adults age 65-plus are on Medicare — and about half have supplemental insurance — they still faced a staggering $54 billion in unpaid medical bills in 2020. A troubling number of those bills were the result of errors, the CFPB said, charging retirees for services they never received.

A 2024 federal audit of Medicare Advantage health plans uncovered similar problems, revealing billions of dollars in overcharges and other payment errors.

Spotting a medical bill error can save you hundreds, or even thousands of dollars, Palmer says. And you don’t have to be an expert to catch medical billing mistakes.

Here are eight ways to check your medical bills for errors and get them fixed.

1. Request an itemized bill and review it carefully

Many medical providers, especially hospitals, don’t include an itemized list of charges when they bill you. Instead, they lump all the charges together in what's called a “summary” bill, with a “total due” at the bottom.

If your bill does not include a detailed list of charges, call the doctor or hospital’s billing office and ask for an itemized invoice to make sure you’re being charged only for the services you received, Palmer says.

You may receive additional statements from physicians, surgeons or specialists — such as anesthesiologists, radiologists and pathologists — who are not employees of the hospital or facility where you were treated. Request itemized bills from those providers, as well.

2. Wait before you pay

Some providers send bills before your insurance company has had time to process the claim, which can make it seem like you owe more than you actually do, says Caitlin Donovan, a spokesperson for the Patient Advocate Foundation, a nonprofit that helps patients resolve billing problems.

When you receive a bill, check the “insurance payment” or “plan payment” line. If it’s blank, your insurer likely hasn’t processed the claim yet.

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Moreover, don’t pay a medical bill until you receive your Explanation of Benefits (EOB) or Medicare Summary Notice (MSN) and confirm the services, dates and what you owe, Donovan advises: “You don’t want to be paying thousands of dollars out of pocket when you only need to pay a copay.”

If you’re on traditional Medicare with a supplemental plan, Palmer says to be extra cautious because “you should barely ever pay out of your own pocket.”

3. Double-check basic facts

Even a small mistake, like an incorrect date of birth, can lead to a claim denial or a significant overcharge, says Beth Morgan, founder and president of Connecticut-based Medical Bill Consultants. For example, one of Morgan’s clients kept getting mixed up with a younger relative who had the same name, resulting in repeated billing issues.

Electronic health records, while meant to reduce errors, can sometimes introduce problems. Morgan recalls a physical therapy patient: “On the first note, [the health care provider] called her a female. All the rest of the notes for the same therapy” referenced a male, she says. “My guess is the doctor, the therapist or whoever, wrote the note for another patient and just copied it over and put the same note in her chart.”

What is the No Surprises Act?

Surprise medical bills — which often occurred when patients had little or no say in where they received care or who provided it — became illegal in January 2022 under the No Surprises Act. (Surprise billing was already prohibited under Medicare and Medicaid.)

The law provides Americans with these protections:

Bans surprise billing for emergency services, including air ambulance services.
Bans out-of-network cost sharing for all emergency and some non-emergency services.
Forbids out-of-network providers to bill patients for ancillary care (like an anesthesiologist or assistant surgeon) at in-network facilities.

To protect yourself, make sure your name, address and insurance details are correct in your health care provider’s notes — many providers offer access to them through a secure online portal — and on any medical bills you receive. Also review your bills carefully to confirm the dates of service are accurate and that they correctly describe your care.

4. Make sure the numbers add up

Check quantities of medications and supplies on the bill, too. If a coder mistakenly adds a 0 to a number, it could add hundreds or thousands of dollars to your bill. Case in point: Morgan had a client who was charged $10,000 for a toiletry item that was supposed to cost only 10 cents.

Hospitals charge by the minute for operating-room time, so it's a good idea to check that they are billing you only for how long you were in the operating room, Palmer says. “You can always ask for your medical record to see what time the surgery actually started and stopped,” she adds. The same goes for the time you spend in recovery.

5. Watch out for duplicate charges and bills

Duplicate charges are a common error, says Adria Gross, founder and CEO of MedWise Insurance Advocacy, which helps elder law attorneys and patients with complicated medical bills.

Sometimes, two doctors bill you for the same service. Another common issue: a provider may send the same bill more than once, asking you to pay twice for the same care. In other cases, bills arrive months after the care was provided, which can cause an insurance denial.

Gross recommends keeping a record of what you’ve been billed for and what you’ve paid.

6. Verify that you received every listed treatment or service

If you were scheduled for a test or procedure but it was canceled, it could still end up on your bill because no one struck it from your chart. The same goes for medications — sometimes patients are charged for drugs that they never received or that were ordered but not administered, Palmer says.

Pro tip: Ask a family member or friend to keep track of who sees you in the hospital if you aren’t able to do so, as Gross says she’s had clients receive bills from doctors who they’ve never even met.

7. Watch for charges that should already be included

Hospitals may try to bill you for items that should be included in the base cost of your room or procedure, such as extra fees for gloves, gowns or other routine supplies, billing advocates warn.

When it comes to surgery, “anything that is routinely used — it’s integral, you can’t do the procedure without it — [the hospital] can’t bill for that,” Palmer says. “It’s already in the cost of the procedure.”

For example, if you have gallbladder surgery, the sterilized instruments used during the surgery are essential and should be included in the total price, not listed as a separate charge, Palmer says. Also, she notes, under most insurance plans, surgeons aren’t supposed to charge for follow-up office visits if they happen within 10 days for minor surgeries or 90 days for major ones. (Medicare and private insurers maintain lists of surgeries where they classify operations as minor or major surgery.)

8. Fight insurance denials and out-of-network charges

Read the fine print of your health insurance policy so you understand your plan’s copays, deductibles, coverage limits and other key terms. If your insurer denies a claim, ask why, Morgan suggests, because sometimes it’s an easy fix.

If your insurer questions the medical necessity of a treatment, consider asking your doctor to write a letter on your behalf. (The Patient Advocate Foundation has tips for fighting insurance denials.)

If you are being charged for out-of-network care, check to see if you’re protected under the No Surprises Act, which bans out-of-network cost sharing — such as out-of-network coinsurance or copayments — for most emergency and some non-emergency services (see box for more information). In cases where there is no in-network provider nearby, you may be able to persuade your health insurer to cover the service at your policy’s in-network rate, Gross says.

What to Do if You Suspect a Medical Error

If something on your medical bill doesn’t look right, speak up. The 2024 JAMA Health Forum study found that while only 61 percent of people with a medical bill concern contacted the health care provider or insurer’s billing office, and 74 percent of those who did were able to get the mistake corrected.

Here are the steps to take to dispute a medical bill.

Gather the facts

Call the medical provider and ask them to walk you through what each itemized charge covers. If you are fighting an insurance denial, verify that the provider used the correct billing code.

Every medical procedure has a corresponding five-digit billing code. These numerical systems, called Current Procedural Terminology (CPT) for insurance and the Healthcare Common Procedure Coding System (HCPCS) for Medicare, determine how much your provider will be paid by your insurance company. “If the description of something is unclear or a charge seems excessive, you can type the code into Google to get a good idea of what it is,” Palmer says.

Keep detailed records

Save copies of bills, letters and other communication from your health care provider and your insurer. If you call a billing office, “keep notes of who you spoke to, the day it was and what they said,” Gross recommends. “You have to keep really good notes because that is going to help you to fight [a billing error].” After a conversation, ask the representative if he or she can send you an email covering what was discussed, she suggests.

You may need to provide these kinds of records as evidence when you dispute a billing error.

Be persistent

It takes the Patient Advocate Foundation’s professional case managers more than 25 calls to resolve the average case, Donovan says.

If you’ve reached a dead end with the customer service agent you’re speaking to, call back and talk to someone else, or ask for a supervisor, Gross suggests. Don’t be afraid to escalate your dispute to the head of the department. “The one thing I say all the time is, ‘fight for your rights,’” Gross says. “Do not give up.”

Lodge a complaint

If you’re not making headway, you could file a formal complaint with your state, Gross suggests. Depending on the issue and where you live, that might be your state’s department of insurance, consumer protection office or attorney general’s office.

Some patients find success going public, whether it’s posting about the issue on social media, filing a complaint with the Better Business Bureau or leaving a review on a site like Yelp or Google.

Consider bringing in a professional

If tackling a large or confusing medical bill feels overwhelming, consider getting help from a patient advocate. The Patient Advocate Foundation provides free medical billing assistance, including bill negotiating services, to U.S. patients with serious health conditions, except for bills related to mental illness, accidents or maternity care. You could also hire a professional patient advocate; many work on contingency, meaning they take a percentage of the money that they help you save.

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Michelle Crouch is a contributing writer who has covered health and personal finance for some of the nation’s top consumer publications. Her work has appeared in Reader’s Digest, Real Simple, Prevention, The Washington Post and The New York Times.