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What does "not medically necessary" mean on a denial letter?

It means the plan's reviewer decided the service does not meet the plan's written clinical criteria for your situation, which is a judgment about documentation and criteria rather than a finding that the care is bad. It is the most common denial reason, and an appeal usually turns on getting the criteria in writing and answering each one with the record.

Last reviewed Sep 11, 2026 · General information, not legal or medical advice · Apellica is not a law firm

What to do, in order

  1. Step 1

    Ask for the criteria by name

    The plan must identify the internal rule, guideline or protocol it relied on and provide it free on request. Ask which specific criterion was not met and what documentation would meet it.

  2. Step 2

    Ask who reviewed it

    Request the reviewer's specialty. Medical-necessity appeals must be decided by a health professional with appropriate training in the field, who was not involved in the initial denial (29 CFR 2560.503-1(h)(3)(iii)).

  3. Step 3

    Answer each criterion with the record

    A letter of medical necessity from the treating clinician that walks through the criteria point by point, citing the notes, tests and prior treatments, is the core of the appeal.

  4. Step 4

    Request a peer-to-peer if offered, and file on time

    A peer-to-peer conversation between your clinician and the plan's physician can reverse the denial before the formal appeal, but it does not stop the clock. File the written appeal regardless.

The deadline that applies

At least 180 days to file the internal appeal on employer and ACA plans; the plan then has 30 days (pre-service) or 60 days (post-service) to decide, 72 hours if urgent. Medical-necessity denials are eligible for independent external review after the internal appeal (45 CFR 147.136(d)).

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Documents to gather

  • The denial letter or Explanation of Benefits, every page
  • Your insurance card and the plan's summary of benefits or Summary Plan Description
  • The clinical notes and test results that support the service
  • A letter of medical necessity from the treating clinician, written to the plan's criteria
  • The plan's clinical criteria or policy, obtained in writing
  • Records of conservative treatments tried and their results

Go deeper

Related questions

Does 'not medically necessary' mean my doctor was wrong?

No. It means the plan's reviewer, working from the plan's criteria and the documents submitted, did not find the criteria met. Missing documentation is a frequent cause.

Can the plan refuse to send me the criteria?

For employer plans, 29 CFR 2560.503-1(g)(1)(v) and (h)(2)(iii) require the plan to disclose the internal rule relied on and give you all documents relevant to the claim free of charge on request. ACA plans carry the same duty through 45 CFR 147.136.

Is external review worth it?

External review is decided by an independent organisation, is free to you, and binds the plan. It is specifically available for medical-necessity, appropriateness, setting, level-of-care and effectiveness determinations.

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