7 Common Medical Billing Errors That Cost Patients Money
May 27, 2026 · 6 min read
A 2023 study by the Medical Billing Advocates of America found errors in over 80% of hospital bills reviewed. Most patients pay without ever requesting an itemized statement. Here are the seven patterns most worth knowing — and how to spot each one.
1. Duplicate Billing
The same charge appears more than once — same date, same procedure, same amount. This is one of the most straightforward errors to catch and one of the most common. It happens frequently with lab panels, imaging reads, and medication administration charges when a patient is transferred between units or the billing system processes an order twice.
How to spot it: Sort your itemized bill by procedure code and date. Any line that appears more than once for the same day warrants a direct question to the billing department.
2. Unbundled Supply Charges
Standard procedure supplies — sterile trays, surgical kits, basic dressings, gloves — are meant to be included in the facility fee or the base procedure code. When a hospital bills for these separately, it is called unbundling. The most commonly abused code here is CPT 99070, a catch-all "supplies and materials" code that should rarely appear as a standalone charge.
CMS's National Correct Coding Initiative (NCCI) edits explicitly prohibit many of these separate billings, but enforcement relies on insurers and patients catching them.
How to spot it: Look for line items with descriptions like "Sterile Tray," "Surgical Kit," "OR Supplies," or code 99070. Our auditor tool flags these automatically.
3. Upcoding
Upcoding means billing for a more expensive service than was actually provided. An office visit coded as a complex new-patient evaluation (CPT 99205) when it was a routine follow-up (CPT 99213) can result in a charge several times higher than warranted. In inpatient settings, upcoding of diagnosis-related groups (DRGs) inflates the entire hospital stay reimbursement.
When upcoding is systematic and intentional, it constitutes healthcare fraud under the False Claims Act. At the patient level, the practical impact is a larger bill and higher cost-sharing.
How to spot it: Look up the CPT codes on your bill using a free lookup tool (the AMA's CPT database or cms.gov). If the code description doesn't match what you experienced, flag it.
4. Services Not Rendered
You are billed for a procedure, consultation, or test that was ordered in the chart but never actually performed — often because it was cancelled, the patient was discharged first, or a duplicate order was placed. Physical therapy sessions, specialist consults, and imaging studies are common culprits.
How to spot it: Keep notes during your care — what procedures were done, which providers saw you, what tests were taken. Cross-reference against your itemized bill. If you don't recognize a charge, ask for the specific date and time it was administered and who performed it.
5. Incorrect Patient or Insurance Information
A transposed digit in your date of birth, a misspelled name, or a wrong insurance ID number can cause a claim to be rejected by your insurer — and then re-billed directly to you as if you had no coverage at all. This is one of the most preventable errors and one of the most expensive when missed.
How to spot it: Verify your personal and insurance information on every bill and every EOB. If a claim was denied, ask your insurer for the specific denial reason — a demographic mismatch is fixable in minutes and the claim can be resubmitted.
6. Illegal Balance Billing
If you received emergency care at any facility, or non-emergency care at an in-network facility from a provider you did not choose, being billed for the difference between the provider's rate and your insurer's payment is illegal under the No Surprises Act. This is arguably the most financially damaging error on this list, as surprise bills often run into the thousands of dollars.
How to spot it: Check whether the circumstances of your visit qualify for NSA protection. Our auditor tool walks you through this check in under a minute.
7. Operating Room Time Rounding
OR time is billed in increments — typically 15 or 30 minutes. Some facilities round up aggressively, billing a full additional block for a procedure that ran only a few minutes into the next interval. A surgery that took 47 minutes might be billed as 60 minutes (two 30-minute blocks) rather than 45 (one and a half). This is rarely caught because patients don't know what the actual start and end times were.
How to spot it: Request your operative report, which records the exact procedure start and stop times. Compare the billed OR time against those timestamps. Any discrepancy beyond a single rounding increment should be disputed.
What to Do When You Find an Error
Finding an error is the first step — but it only has value if you act on it. Our step-by-step dispute guide walks you through writing a formal dispute letter, escalating to regulators, and protecting yourself from collections while the dispute is resolved.
You can also run your bill through our free auditor tool to automatically detect unbundling patterns and NSA violations before you write a single word of a dispute letter.
Billing errors are common, correction is possible, and the process is more straightforward than most patients expect. The only requirement is that you ask.