Denial Radar

Reference playbook

Decode the denial codes most commonly cited in your segment and the angle to appeal each one. Denial rates can only be measured from your own remits, so contribute your 835s (de-identified, on-device) via the Clean Room to see your real breakdown.

Reddenda holds no denial data for your practice. Nothing on this page is your number.

A denial rate cannot be estimated or benchmarked from public data. It can only be measured from your own 835/ERA remits. The playbook below is X12 code reference, identical for every practice in your segment.

Your denial rate

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Not measured. No 835s contributed.

Dollars tied up in denials

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Cannot be inferred. Needs your 835s.

Local-peer denial median

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Not indexed yet. No contributed peer denials.

Measure it: open the 835 Clean Room →

Commonly-cited denial codes in your segmentX12 reference · not your data

DME denials cluster on authorization and documentation rather than on price: the item is covered, but the paperwork proving it was ordered correctly is what the payer rejects.

CO-197Precert / authorization absent

A required prior authorization, precertification, or notification was not on file.

Medicare Advantage plans apply prior-auth to DMEPOS items that traditional Medicare pays without one, so the same item denies on an MA plan and pays on FFS.

Appeal angle · Supply the auth number if one existed, or request a retro-authorization with clinical justification and any urgent or emergent exception.

CO-16Lacks information / billing error

Something required is missing or invalid. This code is almost always paired with a RARC that names the exact field.

The face-to-face (F2F) encounter and the written order are the two elements most often flagged as missing on DMEPOS claims. Read the paired RARC; it names the exact field.

Appeal angle · Read the accompanying RARC first, supply the named missing element, and resubmit as a corrected claim rather than a formal appeal.

CO-50Not deemed a medical necessity

The payer decided the service was not medically necessary as billed.

Coverage for a DMEPOS item is judged against the LCD's specific qualifying criteria; the chart note must state them in the LCD's own terms, not just describe the need.

Appeal angle · Attach clinical documentation and the applicable coverage policy or LCD showing the service met medical-necessity criteria, and correct any weak diagnosis linkage.

CO-22May be covered by another payer (COB)

Under coordination of benefits, the payer believes another plan is primary.

Secondary-payer sequencing errors are common where a beneficiary carries both a plan and Medicare.

Appeal angle · Submit an updated COB record or the primary payer's EOB establishing this payer's correct order of liability.

CO-18Duplicate claim / service

The payer sees this as an exact duplicate of a claim it already received.

Recurring rental billing generates apparent duplicates when the rental month or modifier is wrong.

Appeal angle · If it is not a true duplicate (different date, site, or units), document the distinction and resubmit; otherwise confirm the original claim's status.

CO-29Timely-filing limit expired

The claim was received after the payer's timely-filing deadline.

Timely filing is the one denial that documentation cannot usually rescue; proof of the original submission is the only lever.

Appeal angle · Provide proof of timely original submission (clearinghouse acceptance report) or document a valid good-cause exception.

Appeal deadlines are set per payer and per plan: read the denial letter. The clock usually starts at the remit date, not the date of service, and a corrected claim is often faster than a formal appeal.