10 Medical Billing Errors That Cost You Thousands

Medical bills can contain duplicate-looking lines, mismatched codes, missing insurance adjustments, or services you do not recognize. Those signs are questions to verify, not proof of an error. Here is what to compare before you pay or dispute a charge.

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 and look for a CPT code that appears more than once. Repeated codes can represent separate professionals, repeat procedures, distinct services, or a billing mistake. Ask the billing office to explain each line and modifier before calling it a duplicate.

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 billed code with the visit summary and ask what documentation supports the selected service level. Time may be one factor, but medical decision-making and other coding rules can also determine the level. A high-level code is a question to verify, not proof of 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, identify the information that appears wrong, and ask whether the provider can correct and resubmit the claim. Then confirm the correction on a revised bill or EOB.

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: Compare the provider bill with the EOB and confirm whether the care and plan are covered by the No Surprises Act or applicable state protections. Emergency services and certain out-of-network care at in-network facilities may qualify, but important exceptions and notice-and-consent rules apply.

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

Medicare fee schedules and hospital price-transparency files can provide reference points, but they are not universal fair-price rulings. Facility fees, setting, geography, payer contracts, and code details can change the comparison. Use a reference gap to ask for an explanation or self-pay policy, not as proof that a charge is unlawful.

How to check:Confirm the exact code, date, setting, and locality before comparing a charge with a CMS fee schedule. For hospital services, also look for the hospital's machine-readable price file and match the payer and plan when possible.

Example: If a hospital charge differs sharply from a matched payer-plan or CMS reference, ask the billing office to explain the setting, units, facility component, and policy used. The comparison alone does not prove an error.

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 analyzer helps organize the review points; Pro letter drafts are gated so generated packets cannot bypass account access.
4. Set a follow-up date — use any response window in the notice, then choose the regulator or appeal path that actually covers the provider, plan, or collector.
5. Ask how payment affects the dispute — if you pay an undisputed amount, label it clearly and keep the receipt.

Four checks that produce useful evidence

Frequently asked questions