---
title: "\"Not medically necessary\" Denial, How to Appeal It"
url: "https://denialfacts.com/denial-reasons/not-medically-necessary"
publisher: "Axion Labs — Denial Facts"
checked: "2026-11-04"
dataset_fixity: "sha256-cda2f9b89c8dde2a74989a35dbe7c0d08ff35dac5456484dc1c03c1b181a67b6"
---

# They say you didn't need the treatment. Your doctor says you did.

The insurer says the treatment was not needed for your condition. This is the denial type independent external review is designed for, because it is a clinical judgment made by someone who has never examined you — and your own doctor's letter of medical necessity directly contradicts it.

## Figures

| Figure | Value |
| --- | --- |
| Claims denied for this reason | 5,794,384 |
| Share of all categorized denials | 5.5% |

## Insurers denying most often for this reason

| Insurer | State | Claims | Page |
| --- | --- | --- | --- |
| Centene Venture Company Florida | Florida | 1,072,715 | https://denialfacts.com/insurers/centene-venture-company-florida--fl |
| Celtic Insurance Company | Texas | 800,203 | https://denialfacts.com/insurers/celtic-insurance-company--tx |
| Blue Cross Blue Shield of Texas | Texas | 597,258 | https://denialfacts.com/insurers/blue-cross-blue-shield-of-texas--tx |
| Superior Health Plan | Texas | 580,621 | https://denialfacts.com/insurers/superior-health-plan--tx |
| Celtic Insurance Company | Missouri | 253,236 | https://denialfacts.com/insurers/celtic-insurance-company--mo |
| Absolute Total Care, Inc | South Carolina | 212,578 | https://denialfacts.com/insurers/absolute-total-care-inc--sc |
| Ambetter of North Carolina Inc. | North Carolina | 211,124 | https://denialfacts.com/insurers/ambetter-of-north-carolina-inc--nc |
| Molina Healthcare of Texas, Inc. | Texas | 209,604 | https://denialfacts.com/insurers/molina-healthcare-of-texas-inc--tx |
| Coordinated Care Corporation Indiana | Indiana | 200,636 | https://denialfacts.com/insurers/coordinated-care-corporation-indiana--in |
| Celtic Insurance Company | Kansas | 176,970 | https://denialfacts.com/insurers/celtic-insurance-company--ks |
| Celtic Insurance Company | Tennessee | 176,938 | https://denialfacts.com/insurers/celtic-insurance-company--tn |
| Buckeye Community Health Plan | Ohio | 160,000 | https://denialfacts.com/insurers/buckeye-community-health-plan--oh |

## A "not medically necessary" denial, at the top of the page

Denial reason, “Not medically necessary”

Your two dates, free

Date on your denial notice

Who pays your claims?

A job, an insurance company pays the claims

A job, my employer pays the claims itself (self-funded)

A job, I do not know which

Marketplace / individual plan I bought myself

Medicare, Medicaid, TRICARE, VA or IHS

Which state?

The reason your letter gives

I'm not sure, I'll paste the sentence later

Not medically necessary
Provider out of network
Service excluded from the plan
Experimental or investigational
Referral required
Benefit limit reached
Member not covered
Administrative reason
Other reasons

Show my two dates, free

Put in the date on your notice and you get both federal deadlines as calendar dates, and the body that decides your case at the end.

Free, for a "not medically necessary" denial, and it runs entirely in your browser. The date, the plan type and the state you pick are never sent to us and never stored.

Or let the [$29 Appeal Kit](/appeal-kit) date each step and write the claim-file and external-review requests.

I had my surgery scheduled to be in 2 weeks and I just got the call that insurance deemed it “not medically necessary”. How do I go about fighting

We hear this most. [r/HealthInsurance, “Surgery denied, how do I fight back?”](https://www.reddit.com/r/HealthInsurance/comments/1vhin73/surgery_denied_how_do_i_fight_back/) , read September 3, 2026.

Your insurer calls this “Not medically necessary” . This page is about what that
actually means and what you can do about it.

The clock your letter has to describe, in actual dates

Two dates decide how much room you have. You have 180 days from the date on your denial notice to file the internal appeal, and then 4 months from the final internal denial to ask for an independent external review. If waiting would seriously jeopardize your health you can ask for both to be expedited, decided in about 72 hours . Both timeframes are federal, not your insurer's choice, [29 CFR 2560.503-1](https://www.ecfr.gov/current/title-29/section-2560.503-1) ( [PDF](https://www.govinfo.gov/content/pkg/CFR-2024-title29-vol9/pdf/CFR-2024-title29-vol9-sec2560-503-1.pdf) ) and [45 CFR 147.136](https://www.ecfr.gov/current/title-45/section-147.136) ( [PDF](https://www.govinfo.gov/content/pkg/CFR-2024-title45-vol2/pdf/CFR-2024-title45-vol2-sec147-136.pdf) ), in plain English at [HealthCare.gov](https://www.healthcare.gov/appeal-insurance-company-decision/internal-appeals/) , and your own denial letter states the ones that govern your plan. The PDFs are the same sections on govinfo.gov, which serves them without a challenge page, so an automated reader can check these two dates as easily as you can.

Data verified November 4, 2026 · CMS Transparency in Coverage Public Use File (PY2027 release, PY2025 claims), data.healthcare.gov — US Government public domain

You are not a rare case, and this is the measured version of that: 5,794,384 claims were denied for this reason in the federal file. It is not unusual, it is not a judgment about you, and it is beaten constantly.

- Ranked by volume this is the seventh most common of the 9 denial reasons in the federal file, 5.5% of every categorized denial.

- 91 of the 152 insurer-state records in the file recorded at least one denial under this reason, so it is not one company's habit.

- The single largest block of them sits with Centene Venture Company Florida in Florida: 1,072,715 claims, 18.5% of every denial recorded under this reason nationally.

- It leans hardest in [Indiana](/states/indiana) , where it is 19.7% of all categorized denials, and lightest in Nebraska at 0.1%.

- Across the 91 records that report it the middle one recorded 1,272 claims under this reason, against 1,072,715 at the top of the range and 12 at the bottom, the same reason, two orders of magnitude apart between insurers.

- Insurers in every one of the 29 states in this release recorded it, so nothing about it is local.

- The largest single state block sits in [Texas](/states/texas) : 2,198,296 claims, 37.9% of every denial recorded under this reason nationally.

- The largest reason in the file, other reasons, was recorded 5.83 times as often as this one , 33,793,471 claims against 5,794,384.

- 61 insurer-state records reported none under this reason at all, and the 91 that did averaged 63,675 claims each.

What to do tonight

- Find the reason code on your denial letter. For this denial it will be worded as "not medically necessary" or close to it, with a code beside it. Write that code down: it is one of 9 categories in the federal file and the one that decides which argument works. Answer the code, not the diagnosis.

- Ask your insurer for the clinical criteria they judged you against. Under [29 CFR 2560.503-1](https://www.ecfr.gov/current/title-29/section-2560.503-1) they have to hand you the claim file and the policy they applied, free, on request, and you cannot argue with a checklist you have never read.

- Put both deadlines on your calendar before you go to bed. 180 days from the date on the letter for the internal appeal, 4 months from the final internal denial for external review. The free calculator on this page turns your date into the two calendar dates in about ten seconds. 5,794,384 claims were denied for this reason in the federal file, and the ones that get overturned are overwhelmingly the ones that were still inside the window.

None of those three steps costs anything. Anyone charging you to do them is selling you something you can do yourself in twenty minutes.

Someone who has never examined you read a summary of your file, checked it against a written policy, and decided it didn't qualify. Your doctor examined you and decided it did.

Is this your denial? Look for these words on your letter

“not medically necessary” “does not meet medical necessity criteria” “not medically appropriate” “criteria not met”
Not sure? [Work out which denial you have →](/what-happened)

The first thing to do. Get the policy they judged you against. You cannot argue with a checklist you have not seen , and they have to give it to you free.

Reason to keep going. This is the denial type independent external review is built for, because an independent reviewer judges it on clinical evidence rather than the insurer's own policy.

## What to do about this denial

- Get the exact wording. Ask for the specific plan provision and clinical criteria relied on. The plan must supply it free of charge on request.

- Answer the reason given, not the diagnosis. An appeal that argues the wrong point fails even when the claim is good.

- Get your treating clinician to write the counter. For this denial type especially: a letter of medical necessity citing your records and current clinical guidance is the single most effective document you can add.

- Internal appeal first, then external review. Internal generally within 180 days of the denial; external generally within 4 months of the final internal denial.

Why external review matters here: this denial type turns on medical judgment, which is exactly what external review exists for. Your case is judged by an independent organization that does not work for your insurer, and the insurer is required by law to accept the decision. Nationally, 22.2% (1,092 of 4,918; interval 22.2-23.8% for counts CMS withheld; 32.6% without SelectHealth) of external reviews went in the patient's favor, yet only 1 in 17,061 denials ever gets there.

## Insurers recording the most "not medically necessary" denials

| Insurer | State | Claims | Share of that record's categorized denials |
| --- | --- | --- | --- |
| Centene Venture Company Florida | Florida | 1,072,715 | 11.1% |
| Celtic Insurance Company | Texas | 800,203 | 16.7% |
| Blue Cross Blue Shield of Texas | Texas | 597,258 | 3% |
| Superior Health Plan | Texas | 580,621 | 16.1% |
| Celtic Insurance Company | Missouri | 253,236 | 15.5% |
| Absolute Total Care, Inc | South Carolina | 212,578 | 17% |
| Ambetter of North Carolina Inc. | North Carolina | 211,124 | 16% |
| Molina Healthcare of Texas, Inc. | Texas | 209,604 | 30.2% |
| Coordinated Care Corporation Indiana | Indiana | 200,636 | 20% |
| Celtic Insurance Company | Kansas | 176,970 | 16.8% |
| Celtic Insurance Company | Tennessee | 176,938 | 11.3% |
| Buckeye Community Health Plan | Ohio | 160,000 | 15.6% |
| Celtic Insurance Company | Alabama | 159,371 | 16% |
| Celtic Insurance Company | Oklahoma | 135,898 | 15.1% |
| Health Net of Arizona, Inc. | Arizona | 126,574 | 17.2% |
| Ambetter of Magnolia Inc. | Mississippi | 119,877 | 11.9% |
| Blue Cross Blue Shield of Oklahoma | Oklahoma | 107,070 | 4.8% |
| Ambetter Health of Louisiana, Inc. | Louisiana | 100,921 | 12.5% |
| Meridian Health Plan of Michigan, Inc. | Michigan | 97,740 | 12.9% |
| AmeriHealth Caritas North Carolina, Inc. | North Carolina | 52,036 | 11.6% |
| Blue Cross and Blue Shield of Alabama | Alabama | 23,487 | 0.8% |
| Blue Cross and Blue Shield of NC | North Carolina | 19,569 | 0.5% |
| Highmark Blue Cross Blue Shield West Virginia | West Virginia | 18,750 | 5.1% |
| Health First Commercial Plans, Inc. | Florida | 17,595 | 2.4% |
| QCA Health Plan, Inc. | Arkansas | 15,637 | 16.9% |
| Blue Cross and Blue Shield of Montana | Montana | 14,378 | 5.1% |
| Premera Blue Cross Blue Shield of Alaska | Alaska | 13,562 | 3.6% |
| Highmark BCBSD Inc. | Delaware | 12,983 | 5.7% |
| Wellmark Health Plan of Iowa, Inc. | Iowa | 12,691 | 1.3% |
| SelectHealth, Inc. | Utah | 12,450 | 0.6% |
| Iowa Total Care, Inc. | Iowa | 12,059 | 14.6% |
| Blue Care Network of Michigan | Michigan | 9,690 | 0.7% |
| Blue Cross Blue Shield of Michigan Mutual Insurance Company | Michigan | 7,435 | 2% |
| Community Health Choice, Inc. | Texas | 6,250 | 0.2% |
| Summa Insurance Company, Inc. | Ohio | 5,028 | 5.7% |
| Hawaii Medical Service Association | Hawaii | 4,902 | 2.3% |
| Blue Cross and Blue Shield of South Carolina | South Carolina | 4,037 | 0.1% |
| InStil Health Insurance Company | South Carolina | 3,647 | 13% |
| Wellpoint Insurance Company | Texas | 2,952 | 1.8% |
| University of Utah Health Insurance Plans | Utah | 2,918 | 1.3% |
| Blue Cross Blue Shield of Wyoming | Wyoming | 2,364 | 0.6% |
| Security Health Plan of Wisconsin, Inc. | Wisconsin | 2,214 | 0.9% |
| Wellmark of South Dakota | South Dakota | 1,786 | 2.3% |
| Network Health Plan | Wisconsin | 1,481 | 1% |
| Blue Cross and Blue Shield of Kansas City | Missouri | 1,399 | 3.3% |
| Health Options, Inc. | Florida | 1,272 | 0% |
| HMO Louisiana, Inc. | Louisiana | 1,251 | 0.1% |
| Matthew Thornton Health Plan, Inc. | New Hampshire | 1,251 | 1.2% |
| Blue Cross and Blue Shield of Kansas, Inc. | Kansas | 1,015 | 0.6% |
| Simply Healthcare Plans, Inc. | Florida | 934 | 2% |

## Where a “not medically necessary” denial is common, and where it is not

Every state whose insurers recorded this reason at all, with how much of that state's
categorized denials it accounts for and where it ranks among the reasons recorded there.
Computed from the plan-year 2027 release of the CMS file, not quoted from anyone's summary.

| State | Claims | Share of that state's categorized denials | Rank there |
| --- | --- | --- | --- |
| Texas | 2,198,296 | 5.8% | 7 of 9 |
| Florida | 1,093,553 | 6.8% | 6 of 9 |
| Georgia | 388,002 | 6.7% | 7 of 9 |
| North Carolina | 282,801 | 4.4% | 8 of 9 |
| Missouri | 254,659 | 11.1% | 6 of 9 |
| Oklahoma | 242,994 | 7.3% | 6 of 9 |
| South Carolina | 220,275 | 4.9% | 8 of 9 |
| Indiana | 200,636 | 19.7% | 2 of 8 |
| Alabama | 183,104 | 3.1% | 8 of 9 |
| Kansas | 178,885 | 10.7% | 5 of 9 |
| Tennessee | 177,511 | 4.4% | 7 of 9 |
| Ohio | 165,137 | 7.8% | 7 of 9 |
| Arizona | 126,684 | 6.6% | 6 of 9 |
| Mississippi | 119,877 | 10.4% | 6 of 8 |
| Michigan | 114,897 | 3.6% | 7 of 9 |
| Louisiana | 102,476 | 3.3% | 7 of 9 |
| Illinois | 77,029 | 3.2% | 8 of 9 |
| Iowa | 24,770 | 2.2% | 8 of 9 |
| West Virginia | 18,750 | 5.1% | 3 of 9 |
| Arkansas | 16,608 | 1.1% | 7 of 9 |
| Utah | 15,393 | 0.6% | 8 of 9 |
| Montana | 14,378 | 4.4% | 5 of 9 |
| Alaska | 13,576 | 3.4% | 4 of 9 |
| Delaware | 12,983 | 4.6% | 5 of 9 |
| Hawaii | 4,902 | 2.3% | 6 of 8 |
| Wisconsin | 4,486 | 0.2% | 8 of 9 |
| Wyoming | 2,364 | 0.5% | 9 of 9 |
| South Dakota | 1,994 | 1.8% | 8 of 9 |
| New Hampshire | 1,580 | 1.3% | 7 of 9 |
| Oregon | 976 | 0.6% | 6 of 9 |
| North Dakota | 532 | 0.6% | 8 of 9 |
| Nebraska | 283 | 0.1% | 9 of 9 |

A high share here describes what the insurers in that state wrote on
their denial notices, not whether those denials were right. The spread runs from Texas at 2,198,296 claims down to Nebraska at 283.

## How big this reason is next to the other 8

The same file, the same year, every other categorized denial reason expressed as a
multiple of the 5,794,384 claims denied as “not medically necessary”.

| Denial reason | Claims | Against this page's reason |
| --- | --- | --- |
| Other reasons | 33,793,471 | 5.83× |
| Administrative reason | 17,933,106 | 3.09× |
| Service excluded from the plan | 13,973,937 | 2.41× |
| Referral required | 10,051,768 | 1.73× |
| Provider out of network | 9,391,760 | 1.62× |
| Member not covered | 8,283,170 | 1.43× |
| Benefit limit reached | 5,147,025 | 0.89× |
| Experimental or investigational | 91,890 | 0.02× |

## Your evidence checklist, free, and the whole list

This is what decides a "not medically necessary" appeal. Four of these eleven items are things
your plan must hand you free of charge on request under the federal claims
procedure regulation. Ask for them before you argue: an appeal written without them is argued
against criteria nobody in the room has read. Work down it in order.

| What to get | Why it decides the appeal | Where it comes from |
| --- | --- | --- |
| The denial letter and the Explanation of Benefits | The stated reason is what your appeal has to answer, and the date on it starts the 180-day clock. Everything else follows from these two facts. | You already have it |
| The complete claim file | Everything relied upon in the decision, and everything submitted, considered or generated while making it, whether or not it was relied upon. 29 CFR 2560.503-1(m)(8)(i) and (m)(8)(ii). | The plan, free on request |
| The medical policy or clinical criteria applied to your claim, with its last review date | This is the checklist you were actually judged against. (m)(8)(iv) makes the plan's policy for your diagnosis relevant "without regard to whether" the plan relied on it, so it cannot be withheld on that basis. You cannot rebut criteria you have not read. | The plan, free on request |
| The identity and specialty of the reviewer who denied you | (h)(3)(iv) entitles you to the identification of medical experts whose advice the plan obtained. (h)(3)(iii) requires the appeal to be decided in consultation with a professional with appropriate training in the field of medicine involved, if it was not, that is an argument in itself. | The plan, free on request |
| The full plan document or Evidence of Coverage in force on the date of service | Summaries are compressed and are frequently broader than the contract they summarize. Argue from the contract, not the summary. | The plan, free on request |
| Your treating clinician's letter of medical necessity | Written against the plan's own criteria, item by item, once you have the policy. A letter that says "this patient meets criteria 2a, 2c and 3, documented at ..." is worth far more than one asserting the treatment is needed. | Your clinician |
| Medical records evidencing each criterion in the plan's policy | The reviewer is ticking boxes. Point to the page in the record that satisfies each one. | Your clinician or records office |
| Records of treatments already tried, with dates, doses and outcomes | Plans deny on the basis that a required step was skipped. Dates, durations and outcomes close that door. | Your clinician or pharmacy |
| Published guidelines or trial evidence for your condition | Under (h)(2)(iv) the plan must consider everything you submit "without regard to whether" it was in front of the original decision-maker, including evidence that did not exist when they denied you. | Free, specialty society and journal sites |
| A dated log of every call: who you spoke to, what was said, the reference number | Deadline and procedure arguments are won on evidence of what was said and when. | You, from today onward |
| Proof of how and when you sent everything | Tracked mail, or the plan's portal with a screenshot of the submission confirmation. | You, from today onward |

For this denial specifically. Ask for a letter of medical necessity written against the plan's own criteria, send them the policy document you obtained in Step 1. A letter that says "this patient meets criteria 2a, 2c and 3 as documented on ..." is worth far more than one that says the treatment is needed.

Does a "not medically necessary" denial qualify for independent external review? Yes. This is squarely a medical-judgment denial, which is the core category external review exists for. Whatever the answer, your internal appeal rights are unaffected, always run that.

Work out your two deadlines

Put the date from your notice in and get the two calendar dates, with the days remaining.

Date on your denial notice

Which denial is this?

First denial (I have not appealed yet)

Final internal denial (my appeal was refused)

Show my deadlines

Runs entirely in your browser, the date you type is never sent to us and never stored. [Open the full calculator →](/appeal-deadline-calculator)

Or let the [$29 Appeal Kit](/appeal-kit) date each step and write the claim-file and external-review requests.

## The letter that gets you items 2 to 5, published in full, free

This is the document-request letter, complete and unredacted. It uses four federal rights to
make your plan hand over its entire case before you write a word of your appeal. Send this first,
whatever your denial reason. The Kit fills it in from your details and pairs it with the letters
for the appeal itself, but the letter below works exactly as it stands.

Open the full letter ▸

[Your name]
[Your address]

[Today's date]

[Insurer name]
Appeals Department
[Address from your denial letter]

RE: Request for claim file and plan documents
Member name: [Your name]
Member ID: [Member ID]
Claim / reference number: [Claim number]
Date of service: [Date of service]
Date of denial notice: [Date of denial]

To whom it may concern,

I am appealing the denial of the claim above. Before I submit my full appeal, I am
requesting the documents I am entitled to receive, so that my appeal can address the
actual basis of your decision.

Under 29 CFR 2560.503-1(h)(2)(iii), I am entitled, upon request and free of charge, to
reasonable access to and copies of all documents, records and other information relevant
to my claim. Paragraph (m)(8) defines what is relevant. On that basis I request:

1. The complete claim file, including everything relied upon in making this determination,
and everything submitted, considered or generated in the course of making it, whether or
not it was relied upon. (m)(8)(i) and (m)(8)(ii)

2. Any statement of policy or guidance held by the plan concerning the denied treatment or
benefit for my diagnosis, whether or not it was relied upon in this decision. This
includes the medical policy, clinical criteria, coverage guideline or technology
assessment applied to my claim, and the date it was last reviewed. (m)(8)(iv)

3. The identification of any medical or vocational experts whose advice was obtained on
behalf of the plan in connection with this determination, whether or not that advice was
relied upon, including their specialty and board certification. (h)(3)(iv)

4. The documents demonstrating compliance with the administrative processes and safeguards
required in making this determination. (m)(8)(iii)

5. The specific plan provision on which the denial relies, and the section of the plan
document or Evidence of Coverage in which it appears.

6. A complete copy of the plan document or Evidence of Coverage in force on the date of
service.

Please send these to the address above. I am also giving notice that I intend to appeal,
and I ask that this request not be treated as my appeal or as a substitute for it. I will
submit my full appeal within the applicable deadline.

If you consider that any part of this request falls outside what the regulation requires,
please say so in writing and identify which part and on what basis, rather than declining
the request as a whole.

Sincerely,

[Your name]
[Telephone]

## Questions about a "not medically necessary" denial

##### Is this the denial I have? What words appear on my letter?

Look for these phrases: "not medically necessary", "does not meet medical necessity criteria", "not medically appropriate", "criteria not met". Insurers rarely print the category name itself, they print one of those forms of words. If none of them appear, work through the letter at /what-happened, which sorts denials by the words actually used.

##### How common is this denial?

5,794,384 claims were denied for this reason in the federal data, 5.5% of all categorized denials. It is not a rare or unusual outcome, and it is not a judgment about you.

##### Is this denial worth appealing?

Nationally 26.8% of internal appeals and 22.2% (1,092 of 4,918; interval 22.2-23.8% for counts CMS withheld; 32.6% without SelectHealth) of independent external reviews are overturned, and only 1 in 17,061 denials ever reaches external review. This denial type turns on medical judgment, which is precisely the category external review exists for, and the reviewer does not work for your insurer. Both appeals are free, so the cost of trying is your time.

##### Which insurers record the most of these denials?

Centene Venture Company Florida (Florida, 1,072,715), Celtic Insurance Company (Texas, 800,203), Blue Cross Blue Shield of Texas (Texas, 597,258). The full ranked table is on this page and free to use. These are counts of denials recorded under this reason, not overturn rates, the federal file does not report appeal outcomes by denial reason.

##### What evidence should I gather?

The full checklist is published on this page free. The four items your plan must give you free of charge on request are the complete claim file, the medical policy or clinical criteria applied to your claim, the identity and specialty of the reviewer, and the plan document in force on your date of service, under 29 CFR 2560.503-1(h)(2)(iii), (h)(3)(iv) and (m)(8). Ask for a letter of medical necessity written against the plan's own criteria, send them the policy document you obtained in Step 1. A letter that says "this patient meets criteria 2a, 2c and 3 as documented on ..." is worth far more than one that says the treatment is needed.

Of the 9 denial categories in the federal file, "not medically necessary" is the one where people most often argue the wrong point. The single most useful thing on this page is free and takes one paragraph: ask for the criteria they judged you against. An appeal written without them argues against a policy nobody in the room has read, which is a bit like appealing a parking ticket without knowing what the sign said. Get the criteria first. The rest of this page, and the letter published on it, are yours whether or not you ever buy anything from us.

Axion Labs · hello@getaxionlabs.com

[Get my Appeal Kit, $29](/appeal-kit)
Everything you need for a "not medically necessary" denial: your two deadlines, the argument that fits your denial reason, the letters, a brief for your doctor on what the reviewer checks, and the external review request. One payment. No subscription. No cut of your claim. Opens on screen the moment you pay. 14-day refund, no questions, one email to hello@getaxionlabs.com.

Where these numbers come from The 5,794,384 claims recorded under “not medically necessary”, and the insurer-by-insurer table above, are that file’s own denial-reason columns.

Counts: [CMS Transparency in Coverage Public Use File (PY2027 release, PY2025 claims), data.healthcare.gov — US Government public domain](https://data.healthcare.gov/) . Rights and timeframes: [29 CFR 2560.503-1](https://www.ecfr.gov/current/title-29/section-2560.503-1) (180 days, and your free right to the claim file) and [45 CFR 147.136](https://www.ecfr.gov/current/title-45/section-147.136) (4 months, and what qualifies), explained at [HealthCare.gov](https://www.healthcare.gov/appeal-insurance-company-decision/external-review/) . Expedited review is decided in about 72 hours under both sections.

Reading either regulation from a script rather than a browser: eCFR answers automated fetches with a challenge page, so the same two sections are mirrored as government PDFs at [govinfo.gov (29 CFR 2560.503-1)](https://www.govinfo.gov/content/pkg/CFR-2024-title29-vol9/pdf/CFR-2024-title29-vol9-sec2560-503-1.pdf) and [govinfo.gov (45 CFR 147.136)](https://www.govinfo.gov/content/pkg/CFR-2024-title45-vol2/pdf/CFR-2024-title45-vol2-sec147-136.pdf) .

This page presents federal statistics and a general description of appeal rights created by federal law. It is not legal, medical, or insurance advice, and no outcome is guaranteed. Your denial letter and plan documents govern your specific case. Free help is available from your state's Consumer Assistance Program and from the federal Marketplace at HealthCare.gov.

## The pages that answer the next question

- [Denial code CO-50 on the remittance](/denial-codes/co-50) , "not deemed a medical necessity" is the single most common category in the federal file, and it is the one your insurer has to show you the written criteria for. 5,794,384 claims were denied under "not medically necessary" in the federal file.

- [If it was refused before the treatment](/prior-authorization-denied) , a prior-authorization refusal from your insurer runs on the same two federal clocks as a denied claim, and it can be appealed while the treatment is still ahead of you. 5,794,384 claims were denied under "not medically necessary" in the federal file.

- [If your employer pays the claims itself](/self-funded-denial) , then your insurer is only administering the plan, your state's external review has no power over the denial, and the route is federal. It is the first question our own calculator asks. It changes who reviews a "not medically necessary" denial at the end, not the deadline.

- [Before you pay a lawyer](/before-you-call-a-lawyer) , two free appeals run before anyone bills you by the hour, and your insurer has to hand you the claim file for nothing under 29 CFR 2560.503-1. Both free appeals are open to a "not medically necessary" denial.

- [A letter that answers a “not medically necessary” denial](/appeal-letter) , free, dated from your notice, and it names the reason code the letter has to answer.

- [All denial reasons](/denial-reasons) , the 9 categories the federal file counts, ranked by how many claims each one stopped, "not medically necessary" among them at 5,794,384.

## Who wrote this, and when

By Axion Labs · August 19, 2026, updated November 4, 2026

## The two federal clocks

The clock your letter has to describe, in actual dates Whatever else is on the page, these two dates are the page. You have 180 days from the date on your denial notice to file the internal appeal, and then 4 months from the final internal denial to ask for an independent external review. If waiting would seriously jeopardize your health you can ask for both to be expedited, decided in about 72 hours . Both timeframes are federal, not your insurer's choice, 29 CFR 2560.503-1 ( PDF ) and 45 CFR 147.136 ( PDF ), in plain English at HealthCare.gov , and your own denial letter states the ones that govern your plan. The PDFs are the same sections on govinfo.gov, which serves them without a challenge page, so an automated reader can check these two dates as easily as you can.

## How rare the second appeal is

You are not alone, measured rather than said: 83,907,852 in-network claims were denied in a single plan year, and only 4,918 of them, one in 17,061, ever reached the independent review stage. Of the ones that did, 22.2% (1,092 of 4,918; interval 22.2-23.8% for counts CMS withheld; 32.6% without SelectHealth) were overturned.

## What is free here, and what the one paid thing costs

Denied a claim? Insurers upheld 165,863 of the 262,982 internal appeals counted in 2024, 63.1% ( KFF ). The win is at independent external review, and the only way to arrive there is to run the internal stage on time, in the right order, with the record intact. That sequence is what the Appeal Kit is. Get my Appeal Kit, $29 One payment. No subscription. No cut of your claim. Opens on screen the moment you pay. 14-day refund, no questions, one email to hello@getaxionlabs.com. Get my Appeal Kit, $29 Everything you need for your appeal: your two deadlines, the argument that fits your denial reason, the letters, a brief for your doctor on what the reviewer checks, and the external review request. One payment. No subscription. No cut of your claim. Opens on screen the moment you pay. 14-day refund, no questions, one email to hello@getaxionlabs.com.

## What we will not pretend

What we will not pretend. We cannot overturn your denial. Only your plan, or an independent reviewer, can do that. We cannot make your plan cover a service it genuinely excludes. We cannot guarantee external review applies to your denial. It covers medical judgment, experimental or investigational determinations, and rescission, a purely administrative denial may not qualify, and we say so on those pages rather than selling you past it. We have no customer testimonials and publish none. Our evidence is the federal dataset and the regulation cites, both of which you can check.

## Every page on this site

Home Start here Insurers By company States Denial reasons Use cases How to appeal Ranked by denial rate The external-review gap Write the letter, free Deadline calculator Self-funded plan? Prior authorization denied Medicare WISeR denial Denial code CO-50 Before you call a lawyer Attorney for a denied claim Your denial letter United Healthcare denying claims Time limits on a claim Appeal a Medicare denial About Editorial policy How we compare Privacy Terms For machines: llms.txt openapi.json changes.json the composed answer this page as markdown

## Which release these figures are

Which release these figures are Every number on this page is the plan-year 2027 Transparency in Coverage file, issued October 22, 2026, covering plan-year 2025 claims. This is the newest plan year CMS has published: there is no Transparency in Coverage file for a plan year after 2027. The dataset list is at data.healthcare.gov . A test in this site’s build fetches that list on every run and fails if CMS publishes a plan year we have not acknowledged here. Every earlier release, plan-year 2024, plan-year 2025, plan-year 2026, is kept alongside it so the record is visible rather than a single year’s snapshot; /about says what changed between them. From the plan-year 2024 release to the plan-year 2026 release, external reviews filed went from 2,336 to 5,881. Overturned reviews went from 32.8% in the plan-year 2026 release to 22.2% in plan-year 2027, or from 32.6% to 32.6% without SelectHealth. We do not compare filed or overturned counts across plan-years 2026 and 2027. Some issuers may have counted pre-service appeals in their 2026 cells.

## Where these numbers come from

Where these numbers come from Counts: CMS Transparency in Coverage Public Use File (PY2027 release, PY2025 claims), data.healthcare.gov — US Government public domain . Rights and timeframes: 29 CFR 2560.503-1 (180 days, and your free right to the claim file) and 45 CFR 147.136 (4 months, and what qualifies), explained at HealthCare.gov . Expedited review is decided in about 72 hours under both sections. Reading either regulation from a script rather than a browser: eCFR answers automated fetches with a challenge page, so the same two sections are mirrored as government PDFs at govinfo.gov (29 CFR 2560.503-1) and govinfo.gov (45 CFR 147.136) .

## Who publishes this

Denial Facts publishes federal data about health insurance claim denials. We are independent: not affiliated with, endorsed by, or acting for any insurer, government agency, or review organization. We are not a law firm, a medical provider, or an insurance producer, and nothing here is legal, medical, or insurance advice. Data: CMS Transparency in Coverage Public Use File (PY2027 release, PY2025 claims), data.healthcare.gov — US Government public domain. Figures cover individual-market Qualified Health Plans on the federal Exchange and come from the plan-year 2027 release, issued October 22, 2026, covering plan-year 2025 claims. This is the newest plan year CMS has published: there is no Transparency in Coverage file for a plan year after 2027. See where the data comes from .

## Sources

- CMS Transparency in Coverage Public Use File (PY2027 release, PY2025 claims), data.healthcare.gov — US Government public domain: https://data.healthcare.gov/
- 29 CFR 2560.503-1 (180 days, and your free right to the claim file): https://www.ecfr.gov/current/title-29/section-2560.503-1
- 45 CFR 147.136 (4 months, and what qualifies): https://www.ecfr.gov/current/title-45/section-147.136
- HealthCare.gov on external review: https://www.healthcare.gov/appeal-insurance-company-decision/external-review/

Cite: Axion Labs — Denial Facts, ""Not medically necessary" Denial, How to Appeal It", https://denialfacts.com/denial-reasons/not-medically-necessary (checked 2026-11-04). free to quote with the URL.