Denials worked, not written off.

Every denial code explained the way billers actually need it — what it means, why it fired, the fix steps, whether to appeal. Then the appeal letter drafts itself. The 45-minute letter becomes a 5-minute review.

49 denial codes, plain EnglishAppeal letters drafted freeNo PHI, placeholders by designBuilt for small billing teams

The codes eating your work queue

CO 16 — Claim Lacks InformationClaim/service lacks information or has submission/billing error(s) which is needed for adjudication.CO 97 — Bundled Into Another ServiceThe benefit for this service is included in the payment/allowance for another service/procedure that has alrea…CO 45 — Exceeds Fee ScheduleCharge exceeds fee schedule/maximum allowable or contracted/legislated fee arrangement.CO 96 — Non-Covered ChargesNon-covered charge(s). The related remark code identifies why.OA 23 — Prior Payer Adjudication (OA)The impact of prior payer(s) adjudication including payments and/or adjustments. (Use only with Group Code OA)CO 22 — Another Payer Is PrimaryThis care may be covered by another payer per coordination of benefits.CO 197 — No Prior AuthorizationPrecertification/authorization/notification absent.CO 4 — Modifier Missing or InconsistentThe procedure code is inconsistent with the modifier used, or a required modifier is missing.CO 29 — Timely Filing ExpiredThe time limit for filing has expired.

Browse all denial codes →

From ERA to appeal in three steps

1

Look the code up

Plain English, not X12 legalese: what CO 97 actually means and whether it's appealable at all.

2

Follow the fix steps

Corrected claim or appeal? Wrong path wastes 30 days. Each page tells you which and why.

3

Draft the letter

Code-specific arguments and the enclosure checklist, in ~20 seconds. Review, merge, send.

Why small billing teams use it

Frequently asked questions

What is DenialWiz?

A free toolkit for the unglamorous half of medical billing: plain-English denial code explanations with real fix steps, and an AI drafter that writes payer-ready appeal letters for the specific CARC you're working.

Who is it for?

Billers and billing-company teams at small practices — the people working an ERA queue without a denial-management department behind them.

Do you handle patient data?

No. Every tool is designed around placeholders — [PATIENT NAME], [CLAIM NUMBER] — that you merge privately in your own system. Generation inputs are processed transiently and never stored.

Who builds this?

The team behind EstimateWiz, PaystubWiz and other free document tools used by hundreds of thousands of small businesses. Same philosophy: genuinely useful free tools, no accounts, no data hoarding.

Every denial code on DenialWiz

CO codes — Contractual Obligation

CO 16 (Claim Lacks Information) · CO 97 (Bundled Into Another Service) · CO 45 (Exceeds Fee Schedule) · CO 96 (Non-Covered Charges) · CO 22 (Another Payer Is Primary) · CO 197 (No Prior Authorization) · CO 4 (Modifier Missing or Inconsistent) · CO 29 (Timely Filing Expired) · CO 252 (Documentation Required) · CO 109 (Wrong Payer / Contractor) · CO 24 (Covered by Capitation / Managed Care) · CO 50 (Not Medically Necessary) · CO 226 (Provider Info Not Received) · CO 234 (Not Paid Separately) · CO 151 (Frequency / Units Exceeded) · CO 253 (Sequestration Reduction) · CO 119 (Benefit Maximum Reached) · CO 236 (Incompatible Procedure Combination) · CO 59 (Multiple Procedure Reduction) · CO 18 (Duplicate Claim) · CO 11 (Diagnosis Inconsistent With Procedure) · CO 129 (Prior Processing Info Incorrect) · CO 23 (Prior Payer Adjudication Impact) · CO 131 (Negotiated Discount) · CO B7 (Provider Not Certified for Service) · CO 27 (Coverage Terminated (Provider Liability)) · CO 58 (Wrong Place of Service) · CO 26 (Expenses Before Coverage) · CO 39 (Authorization Denied at Request) · CO 31 (Patient Not Identified) · CO 167 (Diagnosis Not Covered) · CO 170 (Provider Type Cannot Bill This) · CO 181 (Procedure Code Invalid on DOS) · CO 198 (Authorization Exceeded) · CO 6 (Age Inconsistent With Procedure) · CO 146 (Diagnosis Invalid for Date) · CO 15 (Authorization Invalid) · CO 13 (Date of Death Precedes Service)

PR codes — Patient Responsibility

PR 96 (Non-Covered (Patient Liability)) · PR 27 (Coverage Terminated (Patient Liability)) · PR 204 (Not Covered by Benefit Plan) · PR 31 (Patient Not Identified (PR)) · PR 119 (Benefit Max Reached (Patient Liability)) · PR 1 (Deductible) · PR 49 (Routine Exam Not Covered) · PR 2 (Coinsurance) · PR 3 (Copayment)

OA codes — Other Adjustment

OA 23 (Prior Payer Adjudication (OA)) · OA 18 (Duplicate (Other Adjustment))

Tools

All denial codes list · Appeal letter generator

Related denial codes

CO 197 denial codeNo Prior AuthorizationCO 24 denial codeCovered by Capitation / Managed CareCO 119 denial codeBenefit Maximum ReachedCO 31 denial codePatient Not IdentifiedAll denial codesThe full CARC list, plain-English