Medical necessity denials are the most substantive denial type in medical billing. They require a genuine clinical argument, not just administrative correction. The payer is saying: "We don't believe this service was medically required for this patient." Your job in the appeal is to show them, with documentation, that it was.
Why medical necessity denials happen
There are three common reasons a payer denies on medical necessity grounds:
- The documentation doesn't support the diagnosis. The ICD-10 code billed doesn't match the clinical picture in the notes, or the notes are vague and don't demonstrate why the service was required.
- The service doesn't meet the payer's coverage criteria. Every payer has medical policies that define the clinical criteria for coverage of specific procedures. If your documentation doesn't address those specific criteria, the payer's utilization review team will deny.
- The diagnosis doesn't support the procedure. The ICD-10 code submitted doesn't have a recognized clinical relationship to the procedure billed.
Before you write the appeal: find the payer's medical policy
This step is skipped by most billing teams, and it is the most important one. Every major payer publishes its medical policies online. Search for the payer name + "medical policy" + the procedure or condition. Download the policy and read the coverage criteria section.
Your appeal needs to address each criterion in the payer's own policy. If the policy says coverage requires "failure of conservative therapy for at least 6 weeks," your appeal needs to document that failure specifically. If it doesn't, the appeal will be denied for the same reason the claim was.
Documentation required for the appeal
- Complete clinical notes from the date of service, not just the problem list or the assessment. The HPI, exam findings, decision-making, and plan all matter.
- History of prior treatment. If the payer's policy requires failed conservative treatment, document every prior treatment attempt with dates and outcomes.
- Diagnostic test results. Lab results, imaging reports, pathology — whatever supports the clinical decision to perform this service.
- Specialist referral or consultation notes, if applicable.
- The treating physician's letter (peer-to-peer request, if available — see below).
Request a peer-to-peer review
For high-dollar medical necessity denials, ask for a peer-to-peer review. This is a phone call between the treating physician and the payer's medical reviewer. It is often the fastest path to overturning a medical necessity denial, especially for procedures where clinical judgment matters more than policy criteria.
Peer-to-peer requests are typically available within 30 to 60 days of the denial date. The billing team initiates the request; the physician makes the call. Brief the physician on the payer's specific coverage criteria before the call so they address those criteria directly.
Writing the appeal
Structure the appeal letter around the seven-part anatomy from the master appeal guide. Every part matters, and the specifics for this denial are below — above all, structure the argument to mirror the payer's medical policy criteria.
Provider and practice information
Open with the identifiers the payer needs to locate the claim.
- Provider's full name and credentials
- Practice or facility name, NPI, and Tax ID
- Provider's NPI and Tax ID
- Contact information
Always include this on your office letterhead.
Accurate patient and claim details
- Patient name, DOB, and member ID
- Claim number, dates of service, and the original denial date
- CPT/HCPCS and ICD codes
These are what payer staff use to locate the claim. The member ID is the identifier they reach for first.
Denial reference and appeal purpose
State the exact CARC code and any RARC codes (not every denial includes one). Quote the payer's stated denial reason verbatim from the EOB or ERA. Do not risk getting the appeal denied before the supporting documentation is even reviewed by arguing the wrong denial reason.
Clinical and policy argument
This needs to be grounded in facts. Explain why the denial is incorrect. Structure your appeal letter around the clinical documentation for clinical denials. For policy disputes, contract disputes, or fee schedule disagreements, structure your appeal letter to refer to those policies or agreements. Name the specific policy or contract term, and state why and how the policy or contract does not support the denial. For Medicare claims, cite the applicable LCD or NCD.
Supporting evidence
Attach numbered exhibits. Clearly identify each item:
- The EOB or remittance advice showing the denial
- Progress notes or operative reports
- Prior auth confirmations
- Clearinghouse batch transmission report with timestamp
- AMA CPT coding guidelines
- The payer's own medical policy
Explicit request for reconsideration
Clearly state what you are requesting: reconsideration, reprocessing, or payment at the contracted rate. Vague phrases like "please review" give the payer room to close the appeal without action.
Signature and credentials
Sign with a named person's full name, credentials, NPI where applicable, and direct contact information. For medical-necessity appeals, a clinician's signature carries the most weight. A named, reachable signer makes follow-up easier and signals the appeal was reviewed by someone accountable.
Medical necessity appeal letter template
Download the fillable Word template. Every bracketed field is a click-and-type control, so you can complete the letter, edit anything you need, and save it onto your own letterhead. Structured to address CARC 50, 55, and 167 denials with the clinical documentation framework payers expect.
Download the Word template