How to Dispute a Medical Bill (and Actually Win)

Studies show up to 80% of medical bills contain errors. Here's how to challenge incorrect charges using federal and state law — and what to do when the billing department ignores you.

Why medical bills are wrong so often

Medical billing is extraordinarily complex. A single hospital visit can generate dozens of billing codes, multiple providers, and several rounds of insurance processing. Studies estimate that up to 80% of medical bills contain at least one error — and hospitals have no financial incentive to catch mistakes that work in their favor.

Common errors include charges for services you never received, duplicate billing, upcoding (billing for a more expensive procedure than what was performed), failure to apply your insurance payment correctly, and — increasingly — balance billing in violation of the No Surprises Act.

Step 1: Get an itemized bill

Your first move is always to request a complete itemized statement of all charges. Most hospitals send a summary bill — a single line that says "inpatient services: $8,400." That summary tells you nothing useful.

Request the itemized bill in writing. Keep a copy of your request. The itemized bill will show every CPT (procedure) code billed. Once you have it, compare each code to the services you actually received. You can look up any CPT code online to see exactly what procedure it describes.

Step 2: Identify the specific violation

Your dispute letter is much stronger when it names a specific legal violation rather than just saying "I think this charge is wrong." Common violations:

• ✓Balance billing after insurance paid — If your insurer already paid their portion on an in-network claim, billing you for the remainder (beyond your co-pay/deductible) may violate the No Surprises Act.
• ✓Surprise billing from out-of-network provider — If you received emergency care or were treated by an out-of-network provider at an in-network facility without meaningful prior notice, the No Surprises Act likely applies.
• ✓Charges for unreceived services — A CPT code on your bill that doesn't match any service you received is a billing error — and may constitute fraud if it was submitted to your insurer.
• ✓Duplicate charges — The same code appearing twice for the same date of service is a straightforward billing error.

Step 3: Contact your insurance company first

Before you write to the provider, call your insurer and ask: "Did you receive a claim from [provider name] for services on [date]? Was it paid? Was any portion denied?" Get the reference number for this call.

If your insurer paid and the provider is still billing you, that's balance billing — and your dispute letter cites this directly. If your insurer denied part of the claim, you may have a parallel insurance appeal to file (see our guide on insurance denial appeals).

Step 4: Write a formal dispute letter

A formal written dispute is categorically different from a phone call. It creates a documented record, triggers legal obligations under HIPAA and the No Surprises Act, and sets a deadline the provider must respond to.

Your letter should include:

Step 5: Escalate if they don't respond

If the provider ignores your letter or rejects your dispute without explanation, you have several escalation paths:

What about medical debt collections?

If your account has already been sent to a collections agency, your rights are the same — but you also have FDCPA protections. You can send a debt validation letter demanding the collector prove the debt is valid before you pay anything. Until they validate, they must stop collection activity.

LetterPerfect is not a law firm. This guide is for informational purposes only and does not constitute legal advice. For legal representation, consult a licensed attorney in your state.