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 EnglishAI appeal letters — 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

Look the code up

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

Follow the fix steps

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

Draft the letter

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

Why small billing teams use it

Appeal-or-fix triage on every code — half of denial work is knowing which path pays; the pages are built around that decision.
Letters that argue the actual code — medical-necessity criteria for CO 50, NCCI logic for CO 97, filing-proof framing for CO 29.
Zero patient data by design — placeholders throughout — nothing to secure because nothing sensitive is entered.
Honest free — email unlock on the generator, fair-use limits, no trial timers.

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.

Related denial codes

CO 197 denial codeNo Prior Authorization CO 24 denial codeCovered by Capitation / Managed Care CO 119 denial codeBenefit Maximum Reached CO 31 denial codePatient Not Identified All denial codesThe full CARC list, plain-English