Home / What We Find
10 COMMON BILLING ERRORS

10 Common Medical Billing Errors (And How to Spot Them)

Medical billing errors cost Americans billions annually. Learn what to look for so you don't overpay.

Updated January 2026
Written by billing experts

Medical billing is complex. Most patients don't review their bills carefully — and hospitals and insurance companies know this. Studies suggest 80% of medical bills contain at least one error.

This guide breaks down the 10 most common billing errors we find when auditing patient bills. For each error, you'll learn what it is, how to spot it, and what to do about it.

What you'll learn:

  • The 10 most common medical billing errors
  • Red flags to look for on your itemized bill
  • Real examples of errors we found (with savings)
  • How AI catches errors humans miss
1

Duplicate Charges

Most Common Found in ~23% of audits

What It Is

The same service, procedure, or supply is billed multiple times. This can happen accidentally (data entry errors) or deliberately. Common examples include billing the same lab panel twice, charging for the same office visit on consecutive days, or repeating the same supply charge.

How to Spot It

  • Look for identical CPT codes billed on the same date or consecutive dates
  • Check if the same medication or supply appears multiple times in the line items
  • Compare your bill against your Explanation of Benefits (EOB) from insurance

💰 Real Example

A patient was charged $456 for a complete blood panel on two separate line items. The total should have been $228. Saved: $228

2

Upcoding

Serious Found in ~18% of audits

What It Is

A provider bills for a more expensive service than what was actually performed. This is sometimes accidental (billing staff doesn't know the correct code) but can also be intentional. For example, billing for a comprehensive office visit when you only had a brief check-up.

How to Spot It

  • Office visits have levels (99201-99205 for new, 99211-99215 for established). If your visit was brief, it shouldn't be a level 4 or 5.
  • Procedures billed don't match what you were told was done
  • Look for modifiers that indicate extended time or complex care that wasn't provided

💰 Real Example

A patient was billed for a level 5 established patient visit ($285) when their visit lasted less than 5 minutes. Level 1 would have been appropriate ($75). Saved: $210

3

Unbundling

Common Found in ~15% of audits

What It Is

Related services that should be billed together under a single code are instead billed separately. This increases the total charge because individual codes often don't reflect the discount that applies to bundled services. Lab panels are a common example — some individual tests cost much more when unbundled.

How to Spot It

  • Lab tests unbundled from panels (e.g., BMP, CBC, CMP should be single panels)
  • Supply codes separate from procedure codes where they should be included
  • Global surgical packages broken into component parts

💰 Real Example

A patient was billed $847 for individual chemistry tests. The same tests as a bundled metabolic panel would have cost $156. Saved: $691

4

Balance Billing (Out-of-Network)

Protected Found in ~12% of audits

What It Is

You receive care at an in-network facility from an out-of-network provider, and then you're billed for the difference between what the provider charged and what your insurance paid. The No Surprises Act (effective 2022) protects patients from this in many scenarios, but violations are still common.

How to Spot It

  • You were treated at an in-network hospital but received separate bills from individual providers
  • Emergency room visits where the ER physician or ambulance service was out-of-network
  • You weren't notified 72 hours in advance that you'd be receiving out-of-network care

💰 Real Example

A patient received a $4,200 balance bill from an out-of-network anesthesiologist at an in-network hospital. Under the No Surprises Act, this was reduced to $380. Saved: $3,820

5

Wrong Contract Rate Applied

Common Found in ~10% of audits

What It Is

The provider bills you the full "chargemaster" rate instead of the negotiated contract rate with your insurance. This happens when billing staff doesn't properly verify your insurance coverage or enters incorrect information.

How to Spot It

  • Charges on your bill are significantly higher than what your EOB shows as the "allowed amount"
  • Your insurance shows they paid a portion, but the provider is billing you for the full charge
  • The provider's billing system shows "self-pay" or "uninsured" rates instead of your insurance contract rates

💰 Real Example

A patient was billed $12,400 for an MRI at the full chargemaster rate. Her insurance's contracted rate was $3,800. Saved: $8,600

6

Services Never Received

Serious Found in ~8% of audits

What It Is

Services, medications, or supplies that appear on your bill were never actually provided to you. This can range from minor items like gauze pads to major services like surgeries or extended hospital stays.

How to Spot It

  • Review your itemized bill against your memory of the visit — did you actually receive all these items?
  • Check if medications are listed that you never received or were already taking at home
  • Hospital stays that extend beyond when you remember being discharged

💰 Real Example

A patient was billed for 5 days of hospital stay when records showed she was discharged after 3 days. Saved: $14,200

7

Coding Errors

Technical Found in ~7% of audits

What It Is

Incorrect CPT (procedure) or ICD-10 (diagnosis) codes are used. Even a single wrong digit can change the meaning entirely. These errors often result in incorrect insurance processing or inflated charges.

How to Spot It

  • The diagnosis code doesn't match the procedure performed (e.g., knee surgery billed with a foot diagnosis)
  • Your insurance denied coverage because the code doesn't match your condition
  • The procedure code describes something more complex than what you received

💰 Real Example

A patient was billed for an arthroscopic meniscectomy ($4,500) when a simple joint injection ($280) was actually performed. Saved: $4,220

8

Preventable Infections & Complications

Federal Law Found in ~5% of audits

What It Is

Under federal law, Medicare will not pay for treatment of certain hospital-acquired conditions that could have been prevented (called "never events"). Some commercial insurers have similar policies. These costs should not be passed to patients.

How to Spot It

  • You developed a hospital-acquired infection (e.g., central line infection, surgical site infection)
  • You experienced a fall or injury while hospitalized
  • Blood incompatibility or objects left inside after surgery

💰 Real Example

A patient developed a catheter-associated UTI during hospitalization and was billed $8,400 for treatment. This should have been covered by the hospital. Saved: $8,400

9

Wrong Patient Information

Administrative Found in ~4% of audits

What It Is

Simple data entry errors — wrong date of birth, wrong insurance policy number, wrong name spelling. While this might seem minor, it can cause insurance claims to be rejected, leading to you being billed instead of (or in addition to) your insurance.

How to Spot It

  • Your insurance denies claims citing policy number mismatches
  • You've been asked to pay as "self-pay" when you have insurance
  • Bills reference dates of service that don't match your actual visits

💰 Real Example

A patient was incorrectly entered as "self-pay" due to a Social Security number typo. Once corrected, insurance covered $6,200 that she'd already paid. Saved: $6,200 (refund)

10

Lack of Financial Assistance

Often Missed Found in ~15% of eligible patients

What It Is

Nonprofit hospitals are required to offer financial assistance (charity care) to qualifying patients, and must inform patients about these programs. Many hospitals fail to advertise this, and patients miss out on reductions or even complete bill forgiveness.

How to Spot It

  • You received care at a nonprofit hospital and have low-to-moderate income
  • You were sent to collections before being offered financial assistance
  • You haven't asked the hospital about their financial assistance or hardship programs

💰 Real Example

A patient with a $22,000 hospital bill applied for financial assistance and received a 70% reduction under the hospital's sliding scale program. Saved: $15,400

Don't Guess If Your Bill Has Errors

Our AI-powered audit finds these errors automatically. Most patients discover errors worth disputing — and save money.

HIPAA Compliant
Finds All 10 Error Types
Results in 48 Hours