Medical Bill Errors: The 7 Most Common Mistakes to Look For
Billing errors are worth checking for, and finding even one gives you grounds to demand a full review. The seven most common: duplicate charges, services never received, upcoding, unbundling, incorrect quantities, wrong patient or insurance details, and balance billing that violates the No Surprises Act. You need a fully itemized bill with procedure codes to check for them. Be skeptical of the widely repeated claim that "80% of medical bills contain errors" — see below for what is actually known.
Do most medical bills really contain errors?
You have probably seen a claim that 70–80% of medical bills contain errors. We looked for the source, and there is no published methodology behind it — it traces back to advocacy-group statements without a sampling frame. We are not going to repeat a number we cannot stand behind.
What is measured: the federal government audits a random, stratified sample of Medicare and Medicaid claims each year through the CERT program to check compliance with coverage, coding, and billing rules. That is a real methodology, but it measures payments from Medicare to providers — not the bill that lands in your mailbox — and its largest category is missing or insufficient documentation rather than proven overcharges.
So the honest position is this: nobody has a trustworthy figure for how many patient bills contain errors. What is certain is that hospital billing is complex and manual, that specific error types are well documented, and that checking your own bill costs you nothing but an hour.
The 7 errors to check for
- Duplicate charges — the same service or item billed twice.
- Services never received — a test, medication, or procedure you did not get.
- Upcoding — a billing code for more intensive (more expensive) care than you actually received.
- Unbundling — charges billed separately that regulations require to be grouped into one.
- Incorrect quantities — being billed for more units of a drug or supply than were used.
- Wrong patient or insurance details — errors that can cause a claim to be denied or misapplied.
- Illegal balance billing — surprise out-of-network charges that the No Surprises Act may prohibit.
How to check your bill
Request a fully itemized statement with CPT/HCPCS codes for every line. Look up unfamiliar codes, compare the bill against your Explanation of Benefits (EOB) from your insurer, and match every charge to your memory of the visit. Flag anything that does not line up.
What to do when you find one
Put the specific disputed items in writing, request a corrected itemized bill, and ask that the account be placed on hold while the provider reviews it. A documented error is one of the strongest reasons a billing office will re-open an account.
Frequently asked questions
What percentage of medical bills have errors?
No reliable statistic exists. The widely repeated "80% of medical bills contain errors" claim has no published methodology behind it. The federal CERT program does audit a random sample of Medicare and Medicaid claims, but it measures improper payments to providers — mostly insufficient documentation — not errors on patient bills. Check your own bill rather than relying on a headline number.
What is upcoding on a medical bill?
Upcoding is when a provider bills a procedure code for more intensive or expensive care than the patient actually received. It inflates the bill and is grounds for dispute.
How do I get an itemized bill to check for errors?
Request it in writing from the billing department. You are entitled to an itemized statement listing every charge with its procedure code.