What to Do When Your Medical Bill Is Wrong: A Step-by-Step Dispute Guide

If you've spotted a charge that looks wrong, you're already ahead of most patients. The vast majority of billing errors get paid because the patient doesn't know what to do next. This is the playbook.

Phase 1 — Document everything. Before you make a single phone call, get the paperwork in order. Pull together the itemized bill, the Explanation of Benefits from your insurer, any Good Faith Estimate you received, and any notes from your appointment about what was actually done. If you don't have an itemized bill, the very first call you make is to request one.

Phase 2 — Call the billing department. Have the bill in front of you. Ask for a written explanation of any specific charge that looks wrong. Use language like: "I'm reviewing my itemized bill and I have questions about the charge for [CPT code or description] on [date]. Can you walk me through what this represents and provide written documentation?"

Get the representative's name. Note the date and time. Ask for a reference or ticket number for the call. If they push you to pay before reviewing, decline politely and reiterate that you're disputing specific charges in writing.

Phase 3 — Handle insurance denials separately. If a service appears as "not covered" or "denied" on your EOB, the dispute starts with your insurer, not the hospital. Per KFF research on ACA marketplace plans, roughly half of denials that get appealed are reversed. Your insurer is required to provide a denial reason in writing. Common ones — "not medically necessary," "experimental," "out-of-network," "no prior authorization" — each have a different appeal path. Ask the insurer for the formal appeals process and the deadline. Most plans give you 180 days from the denial to file.

Phase 4 — Send a written dispute. Phone calls don't create a paper trail. A written dispute does. Send a letter to the provider's billing office that includes:

— Your account number and the date(s) of service — Each disputed charge, the CPT code, and the amount — Why you believe the charge is incorrect (cite the EOB, your records, the Good Faith Estimate, or whatever you have) — What you're requesting (correction, removal, or itemized justification in writing) — A reasonable deadline (30 days is standard)

Send it certified mail with return receipt. Keep a copy. Federal law requires the provider to respond, and many disputes are resolved at this stage simply because someone in billing actually reads the letter.

Phase 5 — Escalate. If the provider refuses to correct an error, you have options:

— File a Good Faith Estimate dispute. If the bill exceeded a written estimate by more than $400, the federal Patient-Provider Dispute Resolution process costs $25 and a dispute resolver issues a binding decision. — File a No Surprises Act complaint. If the bill involves emergency care, an out-of-network provider at an in-network facility, or air ambulance, file with CMS or call 1-800-985-3059. — File a state insurance complaint. Every state has a department of insurance with a consumer complaint process. They can pressure insurers to resolve denials. — Get help. The Patient Advocate Foundation provides free case management. Dollar For helps patients apply for hospital charity care. — File a CFPB complaint. If a debt collector has been pursuing the disputed bill aggressively or against the Fair Debt Collection Practices Act, the Consumer Financial Protection Bureau takes complaints and gets results.

Phase 6 — Keep records of everything. Every call, every letter, every reference number, every name. Documentation wins disputes. Most billing departments fold quickly when a patient demonstrates they're going to be a documented, persistent problem to ignore.

The whole process takes time. Plan on a few hours of work and a few weeks of back-and-forth. The math usually justifies it: a single corrected error can be worth thousands of dollars, and the only person whose interest is fully aligned with getting your bill right is you.