10 Medical Billing Errors That Cost You Thousands

Studies from the American Medical Association and the National Health Care Anti-Fraud Association estimate that 80% of medical bills contain at least one error. The average overcharge is $1,300. Most patients pay without checking. Here is exactly what to look for and how to fix it.

1. Duplicate charges

The most common billing error. The same CPT code appears twice on the same date of service — same procedure, same provider, billed twice. This happens especially in hospital settings where multiple departments enter charges independently.

How to spot it: Sort your itemized bill by date. Look for any CPT code that appears more than once on the same day. Unless a modifier (like -76 for repeat procedures or -59 for distinct services) is attached, the duplicate is likely an error.

Real example: A patient gets one chest X-ray (CPT 71046). The bill shows 71046 twice — once from radiology, once from the ER — totaling $640 instead of $320. No modifier. That second charge is a duplicate.

2. Upcoding

Upcoding means billing a higher-cost version of a service than what was actually provided. This is the Office of Inspector General's number-one fraud target in healthcare. It often occurs with Evaluation and Management (E&M) codes.

How to spot it: Compare the code billed to what actually happened. The five levels of office visits run from 99211 (brief nurse check, ~$25) up to 99215 (complex 40-minute visit, ~$250). If your 10-minute follow-up was billed as 99215, that is upcoding.

3. Unbundling

Some procedures are meant to be billed as a single package. When a provider splits them into separate line items — each with its own charge — that is unbundling. CMS publishes the National Correct Coding Initiative (NCCI) edits that define which codes cannot be billed together.

How to spot it: Look for multiple related procedure codes on the same date. Classic examples include billing a comprehensive metabolic panel (80053) alongside its component tests (sodium, potassium, glucose individually), or billing a colonoscopy (45380) alongside a diagnostic lower GI endoscopy (45378) that is included in the colonoscopy.

Why it matters: Unbundling can inflate a $300 lab panel to $900+ by billing 14 individual tests instead of one comprehensive code.

4. Wrong patient information

Misspelled names, wrong dates of birth, incorrect insurance ID numbers, or wrong policy group numbers cause claims to be denied — and the bill lands on you. Data entry errors are extremely common in high-volume billing departments.

How to spot it: Check every field on the bill: name, DOB, address, insurance info, policy numbers. One wrong digit in your insurance member ID means the claim was never submitted to your plan.

What to do: Call the billing department, point out the error, and ask them to resubmit the claim with corrected information. They must do this — you are not responsible for their data entry mistakes.

5. Illegal balance billing

Balance billing is when an in-network provider bills you the difference between their full charge and what insurance paid. If you went to an in-network facility and an out-of-network provider treated you (common with anesthesiologists, radiologists, and ER physicians), the No Surprises Act (2022) makes surprise balance billing illegal.

How to spot it: Your EOB shows insurance paid $800 for a procedure. The provider billed $2,000 and sends you a bill for $1,200. If the provider was at an in-network facility, or you went to an ER, that $1,200 balance bill likely violates federal law.

What to do: Cite the No Surprises Act in your dispute letter. File a complaint with CMS if the provider refuses to adjust. Our bill analyzer flags potential balance billing violations automatically.

6. Charges for services never received

Phantom charges. A procedure or test appears on your bill that you never had. This happens more than you'd think — especially in hospital stays where orders are entered into the system but never actually performed, or where a procedure was cancelled after being logged.

How to spot it: Cross-reference every line item against your discharge summary and any notes from your visit. If there is a charge for a procedure you do not remember and it does not appear in your medical records, request the clinical documentation from the provider. They must prove the service was performed.

7. Incorrect quantities (MUE violations)

CMS publishes Medically Unlikely Edits (MUEs) — the maximum number of units for a code that a provider can bill per encounter. Billing 8 units of physical therapy (97110) in a single session exceeds the MUE limit of 4 and signals an error.

How to spot it: Look at the "units" column on your itemized bill. Common violations include excessive physical therapy units, drug infusion hours that exceed the appointment length, and lab test quantities that do not match the number of specimens collected.

8. Inflated operating room time

Operating room charges are billed in 15-minute increments, and each increment can cost $150-$300. If your 45-minute procedure was billed as 90 minutes of OR time, you are paying double. OR time inflation is one of the hardest errors for patients to catch because most people do not know their exact time in surgery.

How to spot it: Request the anesthesia record from the hospital. It logs the exact start and end time of your procedure. Compare those times to the OR charges on your bill.

9. Incorrect procedure or diagnosis codes

A wrong ICD-10 diagnosis code or CPT procedure code can cause your insurance to deny the claim — leaving you with the full bill. Example: a routine screening colonoscopy (covered at 100% preventive) coded as a diagnostic colonoscopy (subject to deductible and copay) because the wrong diagnosis code was attached.

How to spot it: Compare the ICD-10 codes on the claim to your actual diagnosis. If you went in for a routine screening but the bill shows a diagnostic code, the coding was wrong. Ask the provider to correct and resubmit.

Impact: A single wrong digit in a 5-character CPT code can change a $200 office visit into a $3,000 surgical procedure. Always verify the codes match the services you received.

10. Prices far above fair market rate

There is no law that requires hospitals to charge "reasonable" prices — but there is a widely accepted benchmark: the Medicare Physician Fee Schedule. Medicare rates represent what the federal government has determined is fair payment for a service. When a provider charges more than 200% of the Medicare rate, you have strong grounds to negotiate.

How to spot it: Look up each CPT code on the CMS Physician Fee Schedule (free, public, at pfs.data.cms.gov). If the billed amount is 3x or 4x the Medicare rate, that is the strongest argument in your dispute letter.

Example: A basic metabolic panel (CPT 80048) has a Medicare rate of about $11. Some hospitals bill $250+ for the same test — a 2,200% markup. That is not illegal, but it is absolutely disputable.

Found an error? Here is exactly what to do

1. Request the itemized bill — not the summary. You need every CPT code, quantity, and charge on paper.
2. Document the error — write down which code is wrong, what it should be, and the dollar difference.
3. Send a written dispute letter — certified mail, not email. Cite the specific error and the relevant law. Our AI analyzer generates this letter automatically.
4. Follow up in 30 days — if no response, escalate to your state insurance commissioner and the CFPB.
5. Do not pay while disputing — partial payment can be interpreted as acceptance of the charges.

The numbers behind medical billing errors

Frequently asked questions