The complete list
Every denial code, in plain English.
Every health-insurance denial arrives as a code on your EOB — CO-50, PR-197, and about a hundred others. Find yours below for a plain-English translation, your odds, and how to appeal it. Don't see your code? The free tool covers more, and new codes are added weekly.
| Code | What it means | Odds |
|---|---|---|
| Code 1 | This isn't a denial — it's your deductible. The plan says you pay this part before coverage kick… | low |
| Code 2 | Your share of the bill under your plan's cost-sharing. Not a denial.… | low |
| Code 3 | Your copay. Not a denial.… | low |
| Code 4 | A billing-code mismatch by the provider's office. This is paperwork, not a judgment about your c… | high |
| Code 5 | The billing office coded WHERE you got care in a way that doesn't match WHAT was done. A paperwo… | high |
| Code 6 | The treatment code and your age don't match in their system — usually a typo or an age-flagged c… | high |
| Code 7 | The billed procedure doesn't match the sex listed in their records. Often a records error — and … | high |
| Code 8 | They're saying this kind of provider doesn't normally do this procedure. A taxonomy-code mismatc… | high |
| Code 9 | Your diagnosis code and age don't line up in their rulebook — a coding slip more often than a re… | high |
| Code 10 | Diagnosis code and recorded sex don't match. Usually a records or coding error.… | high |
| Code 11 | The diagnosis code and the treatment code don't match up — usually a typo or coding slip at the … | high |
| Code 13 | Their records say the patient died before this care happened — almost always a data error (wrong… | high |
| Code 15 | You had an authorization, but the number on the claim is wrong, expired, or tied to a different … | high |
| Code 16 | Something was missing or wrong on the claim form. Nobody decided your care wasn't covered — the … | high |
| Code 18 | They think this exact claim was already submitted. Often a resubmission crossed paths with the o… | medium |
| Code 19 | They think this should be workers' comp, not health insurance. If it wasn't work-related, say so… | high |
| Code 20 | They think someone else's insurance (like a business's liability policy) should pay first.… | medium |
| Code 21 | They think auto insurance (no-fault/PIP) should pay first — standard after any car-accident-rela… | medium |
| Code 22 | They think another insurance should pay first (a spouse's plan, auto insurance, Medicare). Your … | high |
| Code 23 | Not a denial — this shows how your other insurance's payment affected what this plan paid.… | low |
| Code 24 | Your plan pre-pays your medical group a flat fee, so this claim shouldn't be billed separately —… | medium |
| Code 26 | They say this happened before your coverage started.… | medium |
| Code 27 | They say your coverage had already ended when this happened.… | medium |
| Code 29 | The provider sent the bill too late. In-network providers usually must eat this — not you.… | medium |
| Code 31 | They can't match you to a member. Wrong ID number, name spelling, or date of birth — a five-minu… | high |
| Code 32 | They don't think the patient qualifies as a dependent on this plan.… | medium |
| Code 33 | They say this plan covers only the employee, not family members.… | medium |
| Code 35 | They say you've used up a lifetime cap. For essential health benefits, lifetime dollar caps are … | high |
| Code 39 | The pre-approval request itself was denied before care. Now the claim is following that earlier … | high |
| Code 40 | They're saying your ER or urgent-care visit wasn't a real emergency. The prudent layperson stand… | high |
| Code 45 | The provider charged more than the agreed rate. In-network, the provider writes off the differen… | medium |
| Code 49 | They classified this as routine screening they don't cover. But ACA plans must cover most preven… | high |
| Code 50 | They think you didn't need this care. Your doctor disagrees — and documented medical necessity u… | high |
| Code 51 | They're calling this a pre-existing condition. For ACA-regulated plans, pre-existing condition e… | high |
| Code 55 | They're calling your treatment experimental. External reviewers side with patients on these more… | high |
| Code 56 | They claim there's not enough evidence your treatment works. Same fight as an experimental denia… | high |
| Code 58 | They object to WHERE you got care (hospital vs clinic vs home), not the care itself.… | medium |
| Code 62 | Missing or overrun pre-authorization — the approval either never happened or ran out before care… | high |
| Code 95 | You (or the provider) skipped a step the plan requires — a referral, a network rule, a notificat… | medium |
| Code 96 | A catch-all "we don't cover this." Vague denials are weak denials — make them point to the exact… | medium |
| Code 97 | They bundled this into another payment. A provider-side coding dispute — you generally shouldn't… | medium |
| Code 100 | Not a denial — the insurer paid YOU instead of the provider. You now owe the provider that money… | low |
| Code 107 | This service depends on another claim (like surgery for an assistant surgeon's bill) and the pap… | high |
| Code 108 | Equipment rental/purchase rules weren't followed — like renting past the purchase price or buyin… | medium |
| Code 109 | Wrong insurance company — the claim went to the wrong desk. Pure paperwork.… | high |
| Code 111 | The provider doesn't accept the plan's payment terms, so the plan won't pay them directly.… | medium |
| Code 114 | They're calling the treatment non-FDA-approved. Off-label use of approved drugs is often still c… | high |
| Code 119 | They say you've used up this benefit (e.g., 20 PT visits). Counts are frequently wrong — and ACA… | medium |
| Code 125 | Something on the claim form was wrong. Nobody judged your care — the paperwork failed.… | high |
| Code 129 | They think an earlier claim decision this one depends on was wrong — the claims are tangled toge… | medium |
| Code 136 | Your secondary insurance won't pay because the primary plan's rules weren't followed first.… | medium |
| Code 146 | The diagnosis code used wasn't valid on the day of care — coding-book versions change every Octo… | high |
| Code 149 | A lifetime cap on this specific benefit. Dollar caps on essential health benefits are illegal; v… | medium |
| Code 150 | Downcoding — they think the visit was billed at a higher intensity than the records justify, and… | medium |
| Code 151 | They think you got this care too often. Your doctor's treatment plan is the counter-evidence.… | medium |
| Code 152 | They think the care went on too long — fewer days or sessions than your doctor ordered.… | medium |
| Code 153 | They're disputing the prescribed dose of a medication.… | medium |
| Code 155 | Their records say you refused the care that was then billed. If you didn't refuse, the record is… | medium |
| Code 160 | They're invoking an activity exclusion (often "hazardous activities"). Exclusions are read narro… | medium |
| Code 163 | The claim mentioned documents that never arrived. Nothing was judged — paper went missing.… | high |
| Code 164 | The documents arrived late. The provider's delay generally isn't billable to you in-network.… | medium |
| Code 167 | They say your diagnosis isn't covered by the plan. Check whether the diagnosis code was even rig… | medium |
| Code 170 | The plan doesn't pay this category of provider for this service — common for nurse practitioners… | medium |
| Code 173 | No doctor's order is on file for the service or equipment.… | high |
| Code 175 | The doctor's order is missing required elements (dates, quantities, diagnosis, signature).… | high |
| Code 177 | A catch-all "you weren't eligible." Often stale records — job changes, COBRA gaps, missed premiu… | medium |
| Code 178 | A Medicaid spend-down plan: you must incur a set amount of medical costs before coverage starts,… | medium |
| Code 181 | The billing code used didn't exist or wasn't valid that day — code books update annually.… | high |
| Code 183 | The referral came from a provider the plan won't accept referrals from.… | medium |
| Code 185 | The plan says this specific provider can't bill this service — credentialing or enrollment gaps … | medium |
| Code 189 | The biller used a vague catch-all code when a specific one exists.… | high |
| Code 197 | Nobody got prior authorization first. Usually the provider's job — and emergencies don't need pr… | high |
| Code 198 | You had authorization but used more care than approved (extra days, extra visits).… | medium |
| Code 199 | Two codes on the claim contradict each other — hospital billing plumbing.… | high |
| Code 200 | They say your coverage had lapsed when this happened — often a premium-payment or record-timing … | medium |
| Code 201 | They're pointing to an agreement (like a workers'-comp set-aside) that makes this your cost.… | low |
| Code 202 | They're calling this a comfort item (private room, TV, amenities), not medical care.… | medium |
| Code 204 | A flat "your plan doesn't include this." Sometimes true — sometimes they're reading the wrong pl… | medium |
| Code 210 | The authorization came, but late. A timing foul by the provider — usually not your bill.… | medium |
| Code 216 | An outside review company recommended the denial. You can demand its report and fight its reason… | medium |
| Code 226 | The insurer asked your provider for records and didn't get them. The claim is stuck, not judged.… | high |
| Code 227 | The insurer asked YOU for information (accident details, other-insurance forms) and hasn't gotte… | high |
| Code 242 | Out-of-network denial. Emergencies, no in-network options, and surprise out-of-network providers… | medium |
| Code 243 | Your PCP or network gatekeeper didn't sign off before the care.… | medium |
| Code 247 | A deductible applied because a doctor's service happened inside a facility — cost-sharing math, … | low |
| Code 251 | Records arrived but weren't enough. They want more paper, not a different answer.… | high |
| Code 252 | They just need more paperwork. Nothing has been judged yet.… | high |
| Code 253 | A small automatic federal payment cut (usually 2% on Medicare claims). Providers cannot bill you… | low |
| Code 272 | A vague "you didn't meet the guidelines." Vague denials are weak denials — make them cite the gu… | medium |
| Code 273 | You went past a limit in the plan's guidelines — visits, units, duration.… | medium |
| Code 275 | Your secondary insurance won't pick up what the first plan left you to pay.… | low |
| Code 276 | Your secondary plan won't cover what the primary denied — but if you beat the primary denial, th… | medium |
| Code 279 | Out-of-network denial in a tiered network — you used a non-preferred provider.… | medium |
| Code 286 | They say your appeal itself was too late. Late doesn't always mean over — good cause, notice def… | medium |
| Code 288 | No referral on file. Retroactive referrals fix most of these.… | high |
| Code A1 | A generic denial that must come with remark codes explaining the real reason. The reason is in t… | medium |
| Code B15 | This service only gets paid when a linked qualifying service was billed and covered first — the … | high |
| Code B7 | The provider's certification or enrollment with the plan wasn't active that day. Their paperwork… | medium |
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Start your appeal & set your clock →Common questions
- What do the letters before a denial code mean (CO, PR, OA, PI)?
- CO means contractual obligation — usually the provider absorbs it, not you. PR means patient responsibility — the plan says you owe it. OA is other adjustment and PI is payer-initiated. The number after the letters is the actual reason, explained on each code's page.
- Where do I find my denial code?
- On your Explanation of Benefits (EOB), in a column labeled reason code, adjustment code, or remark code — often written as CO-## or PR-##.