Insurance Said "Not Medically Necessary" — Your Appeal Probably Has a Procedural Ground They're Hoping You Miss
A "not medically necessary" denial sounds final and clinical. It is usually neither. Behind the phrase is a process the carrier has to follow — and a procedural ground in your appeal that does not depend on out-arguing their doctor.
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- "Not medically necessary" is a conclusion. The carrier still owes you the specific reasoning, the criteria it applied, and the records it reviewed.
- The procedural ground most people miss: the denial may not meet the disclosure requirements an adverse decision is supposed to satisfy — specific reason, plan basis, and the rule or guideline relied on.
- The missing fact: you can request the exact internal guideline or criteria used, free of charge, and the credentials of the reviewer who made the call.
- You win these by responding to the carrier's own criteria, not by writing a longer story about why your care matters.
- Get the reasoning, the criteria, and the reviewer on the record before you draft the clinical part of your appeal.
I am a patient, not a lawyer or a doctor. I built this because I needed it — I have read denial letters that announced my care was "not medically necessary" without ever telling me which standard I had supposedly failed. The letters were designed to sound complete. They were not. The thing that moved the needle was making the carrier put its actual reasoning, its actual criteria, and the actual reviewer in writing. This page is about doing that on purpose.
Why "Not Medically Necessary" Is the Start of the Process, Not the End
The phrase "not medically necessary" is doing a lot of work in a denial letter. It sounds like a doctor looked carefully at your situation and concluded the care was unwarranted. Sometimes that is what happened. Very often it is the output of a checklist: your request was scored against an internal clinical guideline, it did not satisfy one or more line items, and the system returned a conclusion. The letter hands you the conclusion and keeps the reasoning. That asymmetry is the carrier's advantage, and reversing it is the whole strategy.
Here is the part most people miss. A denial is an adverse benefit determination, and adverse determinations come with disclosure obligations. For employer-sponsored plans governed by ERISA, the claims-procedure rule at 29 CFR 2560.503-1 requires the plan to give you the specific reason for the denial, reference the specific plan provisions it is based on, and — if an internal rule, guideline, protocol, or other similar criterion was relied on — either provide it or tell you it is available free of charge on request. For decisions that turn on medical judgment, the plan must also explain the scientific or clinical basis applied to your circumstances. A letter that just says "not medically necessary" and stops has not satisfied any of that. The gap between what the letter says and what the rule requires is your procedural ground.
That ground matters because it lets you change the contest. If you accept the denial on its face, your only move is to argue clinical merits — and the carrier is built to win that argument, because they wrote the criteria and they chose the reviewer. But if you demand the specific reasoning and the criteria first, three useful things can happen. You may find the criteria do not actually fit your diagnosis or situation, which is a concrete mismatch your clinician can rebut precisely. You may find the records the reviewer relied on were incomplete, which is a documentation gap you can close. Or you may find the disclosures simply were not provided, which is a procedural defect in the denial itself. Any of the three is a stronger footing than re-arguing necessity from scratch.
There is also a parity angle for certain benefits. The Mental Health Parity and Addiction Equity Act, explained by the U.S. Department of Labor, limits how plans apply treatment limitations — including medical-necessity criteria and prior-authorization requirements — so they cannot be more restrictive for mental health and substance-use benefits than for comparable medical and surgical benefits. If your "not medically necessary" denial involves behavioral health, you have an additional question to put on the record: is the criterion you applied to me applied the same way to comparable medical care? Even outside behavioral health, the spirit of that question — show me the standard and show me it was applied evenly — is part of why disclosure requests are effective.
None of this requires you to become a clinician or a lawyer. It requires you to ask for specific things in a specific order and to capture the answers in writing. The reviewer's credentials matter, because a medical-judgment denial should be made and, on appeal, re-reviewed by appropriately qualified clinicians. The criteria matter, because you cannot rebut a standard you have never seen. The records list matters, because a decision made on an incomplete file is a decision you can reopen by completing the file. The clinical letter your doctor writes is far more powerful when it answers the carrier's actual stated criteria than when it argues into a void.
So the sequence is deliberate. First, get the carrier to state the specific reason, hand over the exact criteria it applied, identify the reviewer's credentials, and confirm which records were reviewed. Second, use those answers to decide which of the three grounds — criteria mismatch, incomplete record, or defective disclosure — is strongest in your case. Only then do you write the clinical rebuttal, aimed precisely at the standard the carrier disclosed. Built in that order, the appeal stops being a plea and becomes a response to the carrier's own paperwork — which is exactly the contest they were hoping you would not start.
What to Do Next
- Find the deadline and the exact reason. Note your internal appeal window from the denial date and isolate the precise stated reason for the determination.
- Request the criteria and reviewer credentials in writing. Ask for the specific guideline or criteria set applied, a copy of it, and the credentials of the clinician who made the decision.
- Confirm the records reviewed. Ask which documents the reviewer actually had, so you can identify and close any gap.
- Pick the strongest ground. Decide whether your case turns on a criteria mismatch, an incomplete record, or a disclosure defect — then lead with it.
- Write the rebuttal to the criteria. Have your clinician respond to the carrier's actual disclosed standard, referencing your documented requests.
Where Claim Lane Fits In
Start free. The Record Check reads your denial language, identifies the likely procedural weakness behind a "not medically necessary" decision, and tells you the next written question to ask.
Record Calls are currently in limited testing and are not open for public purchase yet. When available, a Record Call sends an AI calling assistant to your carrier on your behalf, asks for the specific reason, the criteria applied, the reviewer's credentials, and the records reviewed, and returns the recording, the transcript with identifiers redacted by default, a structured summary, and the captured reference numbers by email.
No outcome is promised. What you get is the documented call — the record of exactly what the carrier said, in a form your appeal can be built around.
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Common Questions About "Not Medically Necessary" Denials
What does "not medically necessary" actually mean on a denial?
It is the carrier's conclusion that, under the criteria it applied, your care did not meet the plan's coverage standard. It is not, by itself, the reasoning. The carrier still owes you the specific reason, the plan provisions it relied on, and the internal guideline or criteria it used. Until you have those, you only have the conclusion, not the basis for it.
What is the procedural ground people miss in these appeals?
That an adverse determination has to meet disclosure requirements. For ERISA-governed plans, the denial must give the specific reason, cite the specific plan provisions, and provide the internal rule or guideline relied on (or state it is available free on request). A letter that just says "not medically necessary" without those elements has a procedural weakness you can press before arguing clinical merits.
Can I get the exact criteria the insurer used?
For ERISA plans, yes. If an internal rule, guideline, protocol, or similar criterion was relied on, you are entitled to a copy free of charge on request. Getting the criteria is what lets your clinician respond to the carrier's actual standard rather than guessing at it — which is usually the difference between a strong appeal and a weak one.
Should my doctor just write a letter explaining the care?
A clinical letter helps, but it is far stronger when it answers the carrier's disclosed criteria point by point. The most effective sequence is to first obtain the specific reason, the criteria, and the reviewer's credentials in writing, then have your clinician rebut the actual standard the carrier used. A letter written into a vacuum is easy for the carrier to wave off.
Authoritative source: the ERISA claims-procedure rule, 29 CFR 2560.503-1, on the federal eCFR.
Claim Lane is an administrative record-building tool, not a law firm or legal service. It does not provide legal or medical advice and does not create an attorney-client relationship. Claim Lane is not affiliated with, endorsed by, or sponsored by any health insurance carrier. Results are not guaranteed.