20 Denial Codes Explained
Insurance Denial Codes — What They Mean and How to Fight Back
Find your denial code below. Each guide explains exactly what it means, why you received it, and your strongest arguments for appeal.
Analyze My Denial Letter — Free →B15
Qualifying Service Not Yet Adjudicated — What It Means and How to Fix It
Got a B15 code? It means your claim depends on another service being processed first. A sequencing issue — not a coverage denial. Get a free viability score.
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CO-109
Claim Sent to the Wrong Payer — What It Means and How to Fix It
Got a CO-109 code? Your claim was sent to the wrong insurance company. A routing error — easily fixed with a correct rebill. Get a free viability score.
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CO-11
Diagnosis Inconsistent With Procedure — What It Means and How to Beat It
Got a CO-11 code? Your diagnosis code doesn't match the procedure billed. Usually a coding fix — not a real dispute. Get a free viability score.
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CO-119
Benefit Maximum Reached — What It Means and How to Beat It
Got a CO-119 code? Your insurer says you've hit a benefit cap. This count is often wrong — and the cap itself may be illegal. Get a free viability score.
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CO-151
Frequency Limit Exceeded — What It Means and How to Beat It
Got a CO-151 code? Your insurer says you've had too many visits or units of care. These limits are often wrong and overturnable. Get a free viability score.
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CO-16
Missing Information Denial — What It Means and How to Fix It
CO-16 means your claim was denied for a missing or incorrect billing detail. Learn what caused it, how to read remark codes, and how to fix or appeal it.
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CO-167
Diagnosis Not Covered — What It Means and How to Beat It
Got a CO-167 code? Your diagnosis isn't covered or is missing. This often happens by billing mistake — not a coverage issue. Get a free viability score.
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CO-18
Exact Duplicate Claim — What It Means and How to Fix It
Got a CO-18 code? Your insurer thinks this claim is a duplicate. Often it's a system error — not an actual duplicate. Get a free viability score.
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CO-197
Prior Authorization Missing — What It Means and How to Beat It
CO-197 means required prior authorization wasn't on file. Learn when this denial can still be reversed and how to fight it — free analysis.
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CO-204
Drug, Equipment, or Service Not Covered — What It Means and How to Beat It
Got a CO-204 code? A specific drug, item, or service isn't covered by your plan. Formulary exceptions can often reverse this denial. Get a free viability score.
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CO-26
Expenses Before Coverage Began — What It Means and How to Beat It
Got a CO-26 code? Your insurer says care happened before your coverage began. Effective dates are often wrong — and fixable. Get a free viability score.
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CO-27
Coverage Terminated Before Care — What It Means and How to Beat It
Got a CO-27 code? Your insurer says coverage had already ended. COBRA election and reinstatement can often reverse this denial. Get a free viability score.
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CO-29
Timely Filing Exceeded — What It Means and How to Beat It
Got a CO-29 code? Your claim was denied for late filing. But if your provider missed the deadline, the denial can be challenged. Get a free viability score.
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CO-4
Denial Code CO-4 Procedure Code / Modifier Mismatch
Got a CO-4 code? Your procedure code and modifier don't match — or a modifier is missing. A coding error, not a clinical denial. Get a free viability score.
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CO-50
Not Medically Necessary — What It Means and How to Beat It
CO-50: Not medically necessary. The most common health insurance denial — and one of the most frequently overturned. Learn how to appeal your CO-50 denial free.
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CO-58
Invalid Place of Service — What It Means and How to Beat It
Got a CO-58 code? Your care was billed with the wrong place-of-service code. A billing location error — almost always correctable. Get a free viability score.
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CO-B7
Provider Not Certified — What It Means and How to Beat It
Got a CO-B7 code? Your provider wasn't credentialed on your service date. A credentialing gap — not your bill to pay. Get a free viability score.
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OA-23
Coordination of Benefits Adjustment — What It Means and How to Fix It
OA-23 reflects how your primary insurance's payment affected your secondary claim. Learn when this adjustment is wrong and how to fix it — free analysis.
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PR-96
Denial Code PR-96 Non-Covered Charge
Got a PR-96 code? Your charge was deemed non-covered. But exclusions must be explicit — and PR-96 is often overturnable. Learn how to dispute it free.
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PR-97
Bundled Charge Billed to You — What It Means and How to Beat It
Got a PR-97 code? It means a bundled service was billed to you as patient responsibility — which is often wrong. Learn how to dispute it free.
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