Insurance coverage denial letter: what it has to tell you, by rule
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What surprised me was how fast everyone just moved on, the doctor suggested
A denial letter is not a summary of a decision. It is a document with required contents, and the requirements are in two federal rules: 29 CFR 2560.503-1, ERISA claims procedure and 45 CFR 147.136, internal claims and appeals and external review. Reading it against that list tells you two things at once: what the plan actually decided, and whether it ran the process properly, which is its own route forward.
The date printed on the letter is the date both clocks start from. 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.
Insurance denial letters: the parts the rules require
| What the letter has to tell you | Where that comes from |
|---|---|
| The specific reason or reasons for the denial, written so you can understand them | 29 CFR 2560.503-1(g)(1)(i) |
| Reference to the specific plan provisions the decision is based on | 29 CFR 2560.503-1(g)(1)(ii) |
| A description of any additional material you would need to send to perfect the claim, and why it is necessary | 29 CFR 2560.503-1(g)(1)(iii) |
| A description of the plan's review procedures and the time limits that apply to them, including your right to bring a civil action under section 502(a) after a denial on review | 29 CFR 2560.503-1(g)(1)(iv) |
| Where an internal rule, guideline, protocol or similar criterion was relied on, either the criterion itself or a statement that a copy will be provided free of charge on request; where the denial is medical necessity or experimental treatment, the scientific or clinical judgment applied to your circumstances, or the same free-of-charge promise | 29 CFR 2560.503-1(g)(1)(v) |
| Enough to identify the claim: the date of service, the health care provider, the claim amount, and a statement that the diagnosis code and the treatment code with their meanings are available on request | 45 CFR 147.136(b)(2)(ii)(E)(1) |
| The denial code and its corresponding meaning, plus the plan's own standard used in denying the claim | 45 CFR 147.136(b)(2)(ii)(E)(3) |
| A description of the internal appeal and external review processes available to you, including how to start one | 45 CFR 147.136(b)(2)(ii)(E)(4) |
| Contact details for the consumer assistance office or ombudsman established under PHS Act section 2793, where one applies | 45 CFR 147.136(b)(2)(ii)(E)(5) |
The deadlines it must state. The review procedures and their time limits are required content, not a courtesy. In practice that means generally 180 days from the date on the notice to file the internal appeal, and generally four months from the final internal denial to ask for the independent external review. If your letter states different periods, the letter and your plan documents govern your case, and the two free stages still exist.
If any of that is missing
Where a plan or issuer fails to strictly adhere to these requirements, the claimant is deemed to have exhausted the internal process and may go straight to external review, and may pursue remedies under section 502(a) of ERISA or state law, at 45 CFR 147.136(b)(2)(ii)(F)(1). That is the rule almost nobody uses: on the numbers above, one denial in 14,369 reached the stage it opens. Do two things the same day. Work your dates out from the date printed on the notice, so the clock is not the thing you lose on. Then ask the plan, in writing, for the missing item and for the claim file: The claim file and the documents relied on are yours free of charge, and any new or additional evidence the plan generates has to be sent to you free of charge in time to answer it, at 29 CFR 2560.503-1(h)(2)(iii) and 45 CFR 147.136(b)(2)(ii)(C)(1). Keep the date you asked.
Denial letter insurance claim: reading the reason it gives
The reason is the part that decides your route, because a denial resting on medical judgment is what independent external review exists for, and an administrative or eligibility denial may not qualify for it. The plan has to print the denial code and its meaning, so the code is readable rather than a mystery. Match the sentence on your letter to the category, and the argument that fits it is on that page, free:
- Other reasons, 28,113,631 claims denied under it nationally
- Administrative reason, 19,612,209 claims denied under it nationally
- Service excluded from the plan, 10,129,111 claims denied under it nationally
- Provider out of network, 8,567,575 claims denied under it nationally
- Referral required, 7,304,650 claims denied under it nationally
- Member not covered, 5,729,108 claims denied under it nationally
- Not medically necessary, 3,968,921 claims denied under it nationally
- Benefit limit reached, 3,646,507 claims denied under it nationally
- Experimental or investigational, 101,612 claims denied under it nationally
If the remittance carries a code rather than a sentence, denial code CO-50 is the commonest of them, and what happened to my claim sorts the letter by the words printed on it.
The appeal route, in order
- Write the date on the notice at the top of a page. Both clocks run from it, not from the day you opened the envelope.
- Ask for the claim file and any criterion applied, in writing, free of charge under 29 CFR 2560.503-1(h)(2)(iii) and (g)(1)(v).
- File the internal appeal, generally within 180 days. The letter generator is free and nothing you type in it reaches us.
- If it is refused, request independent external review, generally within four months of the final internal denial. Your state page says whether that goes to your state or to the federal process.
Questions
What must an insurance denial letter contain?
Nine things, and they come from two places. 29 CFR 2560.503-1(g)(1) requires the specific reason, the plan provisions relied on, what else you would need to send, the review procedures with their time limits and your right to sue afterwards, and the internal rule or clinical judgment used or a promise to send it free. 45 CFR 147.136(b)(2)(ii)(E) adds the claim identifiers, the denial code with its meaning, a description of the appeal routes and how to start one, and the consumer assistance contact. The full list is on this page.
What if my denial letter does not give a deadline?
The deadline still runs, and the omission is itself a failure to meet 29 CFR 2560.503-1(g)(1)(iv). Two things to do the same day: work your dates out from the date printed on the notice with the free calculator on this page, and ask the plan in writing for the missing item. Where a plan fails to run the process as the rules require, the internal stage can be deemed exhausted under 45 CFR 147.136(b)(2)(ii)(F)(1).
How do I read the denial code on the letter?
The code is the fork in the road, because it decides whether independent external review is open to you. The plan has to print the code and its meaning under 45 CFR 147.136(b)(2)(ii)(E)(3), and the diagnosis and treatment codes are available on request under (E)(1) and (E)(2). We publish a page for each reason category in the federal file, and one for the commonest remittance code, CO-50.
Can I get the documents the insurer used?
Yes, free of charge, and asking is the single most useful sentence in a first appeal. 29 CFR 2560.503-1(h)(2)(iii) entitles you to the claim file and the documents relied on, and 45 CFR 147.136(b)(2)(ii)(C)(1) requires any new or additional evidence the plan generates to reach you in time to answer it.
Two dates decide more of this than anything else, and neither is on the front of your letter in a way anyone notices. Work them out tonight, write them on the letter itself, and you have already done the part that is easiest to lose. If your dates are strange, a denial that arrived after the treatment, or a letter with no external-review instructions on it at all, send me the wording with the identifying details removed and I will tell you which clock you are on.
, Andrew at Axion Labs · hello@getaxionlabs.comNo account, no email, no card. Both federal deadlines dated from your notice, with the regulations cited.
- 29 CFR 2560.503-1, ERISA claims procedure, read September 22, 2026
- 45 CFR 147.136, internal claims and appeals and external review, read September 22, 2026
- 29 CFR 2560.503-1, govinfo mirror, read September 22, 2026
- HealthCare.gov on internal appeals, read September 22, 2026
- HealthCare.gov on external review, read September 22, 2026
Counts: CMS Transparency in Coverage Public Use File (PY2026 release, PY2024 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).