How to appeal a medical bill (step by step)

Step 1 — Request an itemized bill

The summary statement you receive in the mail is not enough to appeal. You need the itemized bill, which lists every CPT/HCPCS code, the date each service was rendered, the quantity, and the charge for each line.

Call the billing office and ask for a 'fully itemized statement with CPT codes and revenue codes.' They are generally required to provide it. Put the request in writing as well so you have a paper trail with a date on it.

• Ask for CPT/HCPCS codes, revenue codes, quantities, and per-line charges
• Ask for the date of service on every line
• Request it in writing, and note the date you asked

Step 2 — Line up the bill against your EOB

Your insurer's Explanation of Benefits (EOB) shows what the plan was billed, what it allowed, what it paid, and what it says you owe. The hospital bill shows what the provider wants from you. When those two numbers disagree, one of them is usually wrong.

Pay special attention to the 'patient responsibility' column on the EOB. If the provider is billing you more than that figure and they are in-network, that is often balance billing and it is frequently not allowed under your plan's contract.

Step 3 — Identify the specific problem

A vague appeal ('this seems too high') gets a form letter back. A specific appeal ('line 14 bills CPT 99285 twice for a single ED visit') gets reviewed by a human.

• Duplicate charges — the same code billed twice on one date
• Unbundling — separate charges for services that should be billed under one code
• Upcoding — a higher-complexity code than the visit supports
• Services never rendered — medications or tests you did not receive
• Wrong patient or wrong date of service
• In-network provider billing above the plan-allowed amount

Step 4 — Write the appeal

Keep it to one page. State who you are (name, member ID, claim number, date of service), state the specific line items in dispute, state what you want (reprocess the claim, remove the duplicate, apply the in-network rate), and give a deadline of 30 days for a written response.

Attach the itemized bill and the EOB. Send it in a way you can prove: certified mail, or the insurer's online portal with a screenshot of the confirmation.

Step 5 — Track it and escalate

Log the date you sent the appeal and the date a response is due. If nothing arrives within 30 days, call and reference your letter by date.

If the internal appeal is denied, most plans owe you an external review by an independent reviewer. Your denial letter must tell you how to request one. Self-funded employer plans and marketplace plans both have this route; the deadline is often 4 months from the final denial.