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Medical Billing Errors: How to Spot and Dispute Mistakes on Your Bill

March 6, 2026 · Billing · 10 min read

According to industry estimates, up to 80% of medical bills contain at least one error. Some studies put the number at around 30–40% for significant errors — mistakes that actually affect what you pay. Either way, the odds are not in your favor.

These aren't just rounding errors. We're talking about duplicate charges, services you never received, wrong billing codes, and mathematical mistakes that can add hundreds or thousands of dollars to your bill. The healthcare billing system processes billions of claims per year through a patchwork of codes, software, and human data entry. Mistakes are inevitable.

The good news: you can catch them. And when you do, you have every right to dispute them.

The 10 Most Common Medical Billing Errors

1. Duplicate Charges

The same service appears on your bill twice. This is especially common with lab work, medications, and supplies. If you see two identical line items with the same CPT code and the same date, that's likely a duplicate.

Example: You had one CBC blood test, but your bill shows two charges of $95 each.

2. Upcoding

You're billed for a more expensive service than what you received. This often happens with office visit levels — being charged for a Level 4 or 5 visit (complex, detailed evaluation) when you had a routine Level 2 or 3 visit.

Example: A straightforward 15-minute follow-up is coded as 99215 (high-complexity visit at $350) instead of 99213 (moderate visit at $175).

3. Unbundling

Services that should be billed together under one code (a "bundle") are broken into separate charges, inflating the total. Insurance companies have rules about what should be bundled, but billing departments don't always follow them.

Example: A surgical procedure includes standard prep work, but the prep is billed separately — adding $400 that should have been included.

4. Services Not Rendered

You're charged for something you never received. This can be a simple data entry error or something more problematic.

Example: Your bill includes a charge for physical therapy consultation, but no physical therapist ever saw you.

5. Incorrect Patient Information

Wrong date of birth, misspelled name, incorrect insurance ID — these cause claims to be denied by insurance, and the full bill lands on you. The services were real, but the billing information was wrong.

6. Wrong Diagnosis or Procedure Codes

Medical services are identified by CPT codes (what was done) and ICD-10 codes (why it was done — the diagnosis). If either code is wrong, insurance may deny the claim or pay less than they should.

Example: Your annual physical gets coded as a "sick visit," which means your insurer applies it to your deductible instead of covering it at 100% as preventive care.

7. Balance Billing Errors

An in-network provider bills you for the difference between their charge and the insurance-allowed amount. In-network providers have agreed to accept the allowed amount — billing you the difference (balance billing) is not permitted. The No Surprises Act provides additional protections for certain out-of-network situations.

8. Incorrect Quantities

The number of units is wrong. You received one dose of medication but are billed for three, or you had one hour of a service but are billed for two.

9. Operating Room Time Errors

Hospitals often bill OR time in 15-minute increments. If your surgery took 45 minutes but you're billed for 90 minutes of OR time, that's a significant overcharge.

10. Insurance Not Applied

The provider didn't submit the claim to your insurance and billed you the full amount, or they submitted to the wrong insurer. This is common when you've recently changed insurance plans or have multiple coverage.

How to Spot Errors: Your Checklist

Get the Itemized Bill

If your bill is a summary with a single total, you can't check for errors. Call the billing department and request a fully itemized statement showing every service, code, date, and charge. This is your right — they must provide it.

Need help understanding the itemized bill? See our guide to reading medical bills.

Cross-Reference With Your EOB

Compare the itemized bill with your Explanation of Benefits. The patient responsibility amounts should match. If the bill shows you owe $1,200 but the EOB says $800, there's a discrepancy to investigate.

Check Against Your Memory

Go through each line item and ask yourself:

This is why we recommend keeping notes after medical visits — even just a quick note on your phone listing what tests were done and what medications you were given.

Look Up the CPT Codes

You can search any CPT code online to see what service it represents. If the code description doesn't match what you experienced, flag it. The American Medical Association maintains the CPT code database, and many codes are publicly searchable.

Compare Prices

Use Taven's cost comparison tool to see what the same services typically cost at other facilities. If you're being charged $4,500 for something that averages $1,200 in your area, that's worth questioning — even if it's not technically a "billing error."

How to Dispute a Billing Error

Step 1: Document Everything

Before you call, write down:

Step 2: Call the Billing Department

Call the number on your bill. Ask for the billing department. Here's what to say:

"Hi, I'm calling about account [number]. I've reviewed my itemized statement and I believe there are errors. Specifically, [describe the error — e.g., 'I see a duplicate charge for CPT code 85025 on March 3rd' or 'I'm seeing a Level 4 office visit code but my visit was a routine follow-up']. Can you review these charges and correct them?"

Get the representative's name and a reference number for your call.

Step 3: Follow Up in Writing

After the call, send a written dispute letter. This creates a paper trail. Include:

Send via certified mail with return receipt requested.

Step 4: Contact Your Insurance Company

If the error involves a coding mistake that caused your claim to be denied or underpaid, call your insurer too. They can reprocess the claim with the correct codes.

Step 5: Escalate If Needed

If the billing department won't correct the error:

Preventing Future Errors

Before Your Visit

During Your Visit

After Your Visit

When Errors Become Fraud

Most billing errors are exactly that — mistakes. But systematic patterns of upcoding, billing for services not rendered, or unbundling can constitute healthcare fraud. If you suspect fraud (not just a one-time error), you can report it to:

Under the False Claims Act, whistleblowers can receive a portion of recovered funds in fraud cases involving government programs like Medicare and Medicaid.

The Bottom Line

Medical billing errors are common, but they're not inevitable. By requesting itemized bills, comparing them with your EOB, and questioning anything that looks wrong, you can protect yourself from overcharges that add up quickly.

Your action plan:

Use Taven's bill review tool to quickly check your charges against fair prices in your area. A few minutes of review can save you serious money.