Medical billing errors cost Americans an estimated $68 billion annually according to the Medical Billing Advocates of America. These errors aren't always fraud — many are coding mistakes, insurance mismatches, or administrative errors. But the result is the same: you pay more than you should. Here's what to look for.
Duplicate Charges
The same service or item appears twice on your bill — same CPT code, same date, same amount. This is the most common billing error and the easiest to catch.
How to spot it: Compare each line item on your itemized bill. Look for any code that appears more than once with the same charge amount. Common culprits: supplies, medications, lab tests, and facility fees.
Unbundling (Fragmented Billing)
A procedure that should be billed as a single comprehensive code is split into multiple separate codes. This inflates the total charge because individual components are billed at higher rates than the bundled rate.
How to spot it: CMS has bundled codes for many procedures. If you're billed separately for things that are typically included in a single procedure — like suturing combined with anesthesia, or an EKG combined with an office visit — it's unbundling.
Upcoding
The provider bills a more complex, expensive procedure code than what was actually performed. For example, billing for a comprehensive office visit when a brief visit was sufficient, or billing for a more invasive procedure than what occurred.
How to spot it: Compare the billed CPT code to what you actually received. If you had a brief 10-minute consultation but were billed for a full complex examination, that's upcoding. Check your doctor's notes against the billed code.
Balance Billing (Out-of-Network Providers)
You receive care at an in-network facility but are treated by an out-of-network provider you didn't choose — and then billed for the difference between what the provider charged and what your insurance paid. This is prohibited for emergency services and many non-emergency services under the No Surprises Act (effective January 2022).
How to spot it: Check your EOB for out-of-network charges. If you visited an in-network hospital or surgical center and received care from a provider you didn't select (anesthesiologist, radiologist, pathologist, assistant surgeon), check whether those providers are in-network. Balance billing is one of the most expensive billing errors, often adding hundreds or thousands of dollars to your bill.
Wrong Patient / Wrong Service
Services that were never rendered are billed to your account. This can be a simple data entry error (another patient's charges attributed to you) or, in rare cases, fraud.
How to spot it: Cross-reference every billed service against your personal records: appointment dates, what the doctor told you, any test results or procedure descriptions you received. If a line item describes a service you don't remember receiving, question it.
Incorrect Insurance Rate Applied
The hospital or provider bills you for the full, undiscounted rate when your insurance has already negotiated a lower contracted rate. You're being charged more than the amount your insurer agreed to pay.
How to spot it: Compare the billed amount on your hospital bill to the allowed amount listed on your insurance EOB. If the hospital bill shows a higher number, they're billing you for more than your insurer's contracted rate. You should owe based on the EOB amount, not the provider's original billed amount.
Typos and Data Entry Errors
Simple keystroke errors in CPT codes, diagnosis codes (ICD-10), patient information, or insurance policy numbers can cause claim denials or incorrect billing. The wrong code can mean the difference between a covered service and a denied one.
How to spot it: Check that your name, date of birth, insurance member ID, and policy number are all correct on the bill and on any EOB. Verify the diagnosis code on the bill matches what you were actually treated for.
Preventive Care Billed as Non-Preventive
Under the ACA, most health plans cover preventive care — annual physicals, vaccinations, certain screenings — at 100% with no cost-sharing. But if the provider adds a non-preventive service to the visit or uses the wrong billing code, you can be charged for something that should have been free.
How to spot it: If your annual wellness visit resulted in a bill (beyond a standard copay), or if a vaccination was billed as something other than a preventive service, dispute it. Request a corrected bill that reflects the preventive care codes.
Services Not Pre-Authorized But Billed Anyway
Many insurance plans require prior authorization for certain procedures, tests, or hospital admissions. If the provider performed a service without obtaining required authorization, your insurer may deny the claim — but the provider still bills you for the full amount.
How to spot it: Ask the provider whether they obtained prior authorization. Check your EOB for any denial noting lack of authorization. In many states, providers are required to obtain authorization before performing non-emergency services — failure to do so means the provider, not you, is responsible for the charge.
Medically Unnecessary Denials Treated as Patient Liability
Your insurer declares a procedure or service medically unnecessary and denies coverage. But the hospital continues to bill you for the denied amount. This creates a false appearance that you owe the full charge — when in reality, this should be disputed as an insurance coverage issue, not a patient billing issue.
How to spot it: If you received a denial letter from your insurer marked medically unnecessary and the hospital is now billing you for the full amount, this is a billing error. The hospital should work with your insurer to appeal the medical necessity decision — not pass the cost to you. You have the right to appeal the denial directly, and our letter template covers how to do this.
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