Up to 80% of medical bills contain at least one error, according to the Medical Billing Advocates of America. On a typical hospital bill, that can mean hundreds or thousands of dollars in overcharges that you're paying unnecessarily.

The good news: you can check your bill yourself, and you don't need a medical billing degree to do it. This guide walks you through the process step by step.

Before you start: get the right documents

You need two things:

  1. An itemized bill from the hospital or provider — not the summary statement. The itemized version shows every charge with a CPT/HCPCS procedure code, date of service, and individual price. You have the legal right to request one.
  2. Your Explanation of Benefits (EOB) from your insurance company — this shows what your insurer approved, what they paid, and what you owe. If the provider's bill doesn't match your EOB, that's your first red flag.
If you only have a summary bill with a single total, call the billing department and say: "I'm requesting a fully itemized statement with CPT codes for all charges." They must provide it.

The 5-step bill check

1

Check for duplicate charges

Look for the same CPT code billed twice on the same date. This is the single most common billing error. A 15-minute office visit (99213) billed twice, or the same lab test charged on the same day, is almost always an error.

2

Look for bundling violations

Some procedures are supposed to be billed together (bundled) at a lower rate. When they're billed separately, you pay more. The CMS maintains 190,000+ code-pair rules called NCCI edits that define which codes can't be billed together. For example, a comprehensive metabolic panel (80053) already includes a basic metabolic panel (80048) — billing both is a bundling violation.

3

Compare charges to Medicare rates

Medicare publishes what it pays for every procedure (the Physician Fee Schedule). While hospitals can charge more than Medicare rates, charges that are 300-500% above the Medicare rate are a red flag — especially for routine lab work and office visits. You can look up rates on the CMS website.

4

Verify provider and service details

Check that the provider's NPI (National Provider Identifier) is valid, that the place of service code matches where you received care, and that the dates of service are correct. Wrong facility codes can result in higher charges — an outpatient procedure billed as inpatient, for example.

5

Cross-reference with your EOB

Compare every line item on your bill against your EOB. Your EOB shows the "allowed amount" — the maximum your insurer agreed to pay. If the provider is billing you more than what your EOB says you owe (the "patient responsibility" column), that's a balance billing issue and may violate the No Surprises Act.

Skip the manual work

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Common errors to watch for

Upcoding

Upcoding is when a provider bills a higher-level (more expensive) code than the service actually provided. For example, billing a level 4 office visit (99214, ~$150) when a level 3 visit (99213, ~$110) was actually performed. This is one of the most common and hardest-to-spot errors for patients.

Facility fees

Hospital-owned clinics often charge a "facility fee" on top of the provider's professional fee — sometimes doubling the total cost. If you visited a doctor's office that happens to be owned by a hospital system, ask whether a facility fee was added and whether the same service is available at a non-hospital-owned location.

Operating room time

Surgical bills often include charges for operating room time in 15-minute increments. Errors in the recorded start/end times can add hundreds of dollars. If you had a procedure, check that the billed time is reasonable for the surgery performed.

Anesthesia units

Anesthesia is billed in time units plus a base unit value. Overcharges often come from incorrect time calculations or using the wrong base units for the procedure. Compare the billed time to what your surgical records indicate.

What to do when you find an error

  1. Document everything. Write down the specific charge, the CPT code, the date, and why you believe it's an error. Note the specific billing rule that was violated (e.g., "NCCI edit pair 80053/80048").
  2. Call the billing department. Start with a phone call. Reference the specific line item and ask them to review it. Many errors are corrected with a single call.
  3. Send a written dispute. If the phone call doesn't resolve it, send a formal dispute letter via certified mail. Include your account number, the specific charges you're disputing, the regulatory basis for your dispute, and a request for a corrected bill within 30 days.
  4. Contact your insurer. If the provider doesn't cooperate, contact your insurance company's member services. They have leverage that individual patients don't.
  5. File a complaint. For unresolved disputes, file a complaint with your state's insurance commissioner or the CMS No Surprises Act helpline at 1-800-985-3059.
The key to a successful dispute is specificity. Don't say "my bill is too high." Say "CPT code 80048 on line 4, dated 01/15/2026, is an NCCI bundling violation with CPT 80053 on line 3. Per CMS NCCI edits, these codes cannot be billed together."

Know your rights

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