What "not medically necessary" means on a denial letter

Name: What "not medically necessary" means on a denial letter
Creator: Measured Editorial Team
Published: 2026-08-05

By Measured Editorial TeamPublished August 5, 2026Updated August 12, 2026

Insurance & Cost

"Not medically necessary" means your insurer decided the request did not meet its own written clinical criteria — not that your doctor was wrong. Preauthorization is a decision by a health insurer or plan that a health care service, treatment plan, prescription drug, or durable medical equipment is medically necessary. A denial on that ground can be appealed.

Key takeaways

"Not medically necessary" is a coverage decision measured against the plan's own written criteria, not a clinical verdict on you — and it can be appealed.
The letter is legally required to name the denial code and its meaning, the standard used, the internal criteria (a copy free on request), and any missing information. Read those fields, not the summary line.
Three different situations produce the same label: documentation gaps, a plan wanting an alternative drug tried first, and a flat benefit exclusion. The third changes your next step, because the drug exceptions process may fit better than a clinical argument.
You generally have 180 days to file an internal appeal and four months from the final determination to request external review; urgent cases move in 72 hours.
Coverage always depends on the individual plan, and no appeal outcome can be promised.

Last reviewed: August 5, 2026. This page explains the phrase itself. Deadlines and program-availability details sit in one dated block near the bottom, because those are the parts that change.

The phrase describes a comparison between the paperwork the plan received and a policy document the plan itself wrote, which is why the fix is very often documentary rather than medical.

What it does not mean

It is not a judgment about you as a patient. A notice of adverse benefit determination must describe the plan's or issuer's standard used to deny the claim. The standard belongs to the plan, and the letter must tell you what it was.

It is not final. A denial on medical-necessity grounds can be appealed; an enrollee must file an internal appeal within 180 days (6 months) of receiving notice that the claim was denied.

It is not the same as "not covered." A formulary is the list of prescription drugs covered by a prescription drug plan or other insurance plan offering prescription drug benefits. A drug left off the formulary is a benefit-design decision, not a clinical one. A denial on the ground that the benefit is not offered under the enrollee's health plan can be appealed as well, but with a different argument.

It is not an independent decision — yet. An internal appeal is conducted by the plan or issuer itself and results in a final internal determination, and reviewers deciding it must not have any conflicts of interest. At the next stage, any denial that involves medical judgment where the enrollee or provider may disagree with the health plan can go to external review.

Where the real reason is hiding in your letter

The useful information is in the letter's required fields, not in the summary sentence at the top.

Phrase you see	What it actually is	What you can request
A short code plus a one-line reason	The formal denial reason. A notice of adverse benefit determination must state the specific reasons for the determination, including the denial code and its corresponding meaning.	Coding and other information relevant to the claim, free of charge upon request (29 CFR 2560.503-1(h)(2)(iii)).
A named policy, bulletin, or clinical guideline number	The rulebook you were measured against. The notice must describe the internal guidelines or criterion used and inform the consumer that a copy of the internal requirements will be provided free of charge upon request.	The policy document itself, in writing.
"Based on clinical review" with no reasoning	An incomplete rationale. For a denial based on medical necessity, experimental treatment, or a similar exclusion, the notice must provide an explanation of the scientific or clinical judgment, or state that one will be provided free of charge upon request.	The written explanation of the clinical judgment.
"Insufficient documentation" or a list of missing items	The shortest path to a reversal. The notice must describe any additional information needed to improve or complete the claim.	Nothing — this is your to-do list.
The appeal-rights paragraph near the end	Your clock. The notice must provide notification of internal appeals and external review rights, the plan's review procedures, and applicable time limits.	Confirmation of which deadline applies to your situation.

Once you have those documents, use them: a claimant has the right to a full and fair review, including the opportunity to review and respond with written comments, documents, and records to any evidence or rationale under consideration.

Three things that put this label on a request

Three different situations, not a ranked list; we are not publishing frequency figures we cannot source. The most common GLP-1 denial reasons are cataloged separately.

1. The criteria were met, but the record did not show it

The tell is the letter's missing-information field. If the notice lists specific items — a measurement, a date range, a prior diagnosis — the file was thin, not the treatment wrong. Appeal is the right lever, and the fix is attaching what was named.

2. The plan wanted something else tried first

The tell is language pointing at alternative covered drugs the plan wants tried first. Here the drug exceptions route often matters more than a straight appeal. An enrollee has the right to follow the insurer's drug exceptions process to get a prescribed drug that is not normally covered by the plan; the enrollee's doctor must confirm to the health plan, orally or in writing, that the drug is appropriate for the enrollee's medical condition. Grounds supporting a request include: all other drugs covered by the plan have not been or will not be as effective as the drug requested; an alternative covered drug has caused or is likely to cause side effects that may be harmful to the enrollee; or, where the plan limits the number of doses allowed, the allowed dosage has not worked for the enrollee's condition.

3. It is an exclusion wearing a medical-necessity label

The tell is a letter citing the plan's benefit documents rather than any clinical criterion. Arguing clinical detail against a benefit-design decision goes nowhere; it is still appealable, and the exceptions process may be the better route.

What this looks like on a GLP-1 denial

Measured states that many insurance plans require a prior authorization before they will cover brand-name GLP-1s such as Ozempic, Wegovy, Mounjaro, or Zepbound. Preauthorization is not a promise that the health insurance plan will cover the cost of the service or drug, so an approval at this stage and a paid claim are two separate events.

Form and product matter, because a plan's criteria are written per product. Measured prescribes FDA-approved GLP-1 medications — semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) — plus compounded alternatives when brand medications are unavailable, and oral medications including metformin, topiramate, and bupropion/naltrexone. Measured lists the Wegovy Pill (daily oral semaglutide) as "No insurance required," with medication paid separately from membership. Compounded medications are not reviewed or approved by the FDA for safety or effectiveness.

Telehealth-program eligibility and eligibility under a specific plan's policy are two different tests. Enrolling in a program is not the same as meeting your plan's coverage criteria, and neither is the same as a provider concluding that a given medication is clinically appropriate for you. Your plan's written criteria may differ from all of it, which is why you request the policy document.

For patients with commercial insurance, Measured performs a benefits check to determine which medications may be covered under the patient's plan. Measured's insurance concierge team submits prior authorizations on the patient's behalf and keeps the patient updated on the insurance plan's determination.

What to do in the next 7 days

Find the denial code and its meaning. It is a required field; read it before anything else.
Request the internal criteria in writing. A copy must be provided free of charge upon request; ask by the method the letter specifies.
Request the clinical rationale if the letter gave you a conclusion without reasoning.
Write down every missing item the letter names. That list is your appeal outline.
Confirm your deadline. The internal-appeal window is 180 days from notice of denial.
Ask your prescriber for supporting documentation. Submit any additional information you want the insurer to consider, such as a letter from the doctor.
Start a file. Keep the Explanation of Benefits forms or letters showing what payment or services were denied, plus notes and dates from any phone conversations with the insurance company or doctor — day, time, name and title of the person spoken to, and details of the conversation.

You do not have to do this alone: an internal appeal may be filed by the consumer or by an authorized representative designated in writing, and the Consumer Assistance Program in an enrollee's state can file an appeal on the enrollee's behalf.

Deadlines and dated caveats

An insurer must notify the enrollee in writing of a denial within 15 days when the enrollee is seeking prior authorization for a treatment. An internal appeal must be completed within 30 days if the appeal concerns a service the enrollee has not yet received. A plan must decide an internal appeal within 72 hours of the request when it concerns a denial of a claim for urgent care. An enrollee can file an expedited appeal if the timeline for the standard appeal process would seriously jeopardize their life or their ability to regain maximum function.

If the internal appeal fails, an enrollee must file a written request for an external review within four months after the date they receive a notice or final determination from the insurer that the claim has been denied. Standard external reviews are decided as soon as possible and no later than 45 days after the request was received. The insurer is required by law to accept the external reviewer's decision. External review is free under the federal process, and the plan or issuer pays the independent review organization; only states that expressly allowed a filing fee as of November 18, 2015 may still charge one, capped at $25 per external review.

Two dated exceptions. The Affordable Care Act internal appeals and external review provisions apply only to health plans or policies created or purchased after March 23, 2010, and do not apply to grandfathered health plans. And as of July 1, 2026, the HHS-Administered Federal External Review Process (FERP) is temporarily unavailable for enrollees who live in Alabama, Florida, Georgia, Texas, Wisconsin, or a U.S. territory other than Puerto Rico and whose plan or issuer uses that process; enrollees whose plan or issuer does not use the HHS-Administered FERP should follow the instructions in the notice from their plan or issuer.

Frequently asked questions

Can I appeal a "not medically necessary" denial?+

Yes. A denial on the ground that the requested service or treatment is not medically necessary can be appealed. An enrollee must file an internal appeal within 180 days (6 months) of receiving notice that the claim was denied.

Who decides medical necessity?+

Your plan does, first. An internal appeal is conducted by the plan or issuer itself and results in a final internal determination. Reviewers deciding an internal appeal must not have any conflicts of interest.

Is "not medically necessary" the same as "not covered"?+

No. A formulary is the list of prescription drugs covered by a prescription drug plan or other insurance plan offering prescription drug benefits. A drug can be on the formulary and still be denied on medical-necessity grounds, and a drug can be excluded entirely for reasons unrelated to your chart.

How long do I have to appeal?+

An enrollee must file an internal appeal within 180 days (6 months) of receiving notice that the claim was denied. For external review, an enrollee must file a written request within four months after the date they receive a notice or final determination that the claim has been denied.

Can an outside reviewer overrule my insurer?+

Yes. Adverse benefit determinations involving medical judgment include those based on the plan's requirements for medical necessity, appropriateness, health care setting, level of care, or effectiveness of a covered benefit. The insurer is required by law to accept the external reviewer's decision.

What if waiting would be dangerous?+

In urgent situations an enrollee may request an external review at the same time as the internal appeal, without having completed all of the health plan's internal appeals processes. Expedited external reviews are decided no later than 72 hours after the request was received, or less depending on medical urgency.