Why health insurers deny claims
Every denial has a category, and each category is beaten differently. These are the reasons insurers reported for 104,460,511 denied claims, this figure counts all categorized denials (in- and out-of-network), so it is larger than the 83,907,852 in-network figure cited elsewhere on the site.
| Reason | Claims | Share |
|---|---|---|
| Other reasons | 33,793,471 | 32.4% |
| Administrative reason | 17,933,106 | 17.2% |
| Service excluded from the plan | 13,973,937 | 13.4% |
| Referral required | 10,051,768 | 9.6% |
| Provider out of network | 9,391,760 | 9% |
| Member not covered | 8,283,170 | 7.9% |
| Not medically necessary | 5,794,384 | 5.5% |
| Benefit limit reached | 5,147,025 | 4.9% |
| Experimental or investigational | 91,890 | 0.1% |
Find yours on the denial letter, it will use one of these categories or close to it. Then read the page for that reason: the argument that works is different for each.
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The federal timeframes: 180 days from the date on the denial notice to file the internal appeal, then 4 months from the final internal denial to request independent external review. Put your date in and get the actual calendar dates, with the days remaining.
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Every denial has a category, and the argument that works is different for each one. Find the wording on your own letter first, then read that page, not the other way around. If the letter is vague enough that none of these obviously fits, that is itself the answer: ask them, in writing, for the specific reason and the plan provision behind it. You are entitled to that, it costs nothing, and it is the most useful thing you can send tonight.
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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).