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Denial reference · CARC · 2026 Edition

CARC codes 2026. The complete denial reason reference.

A working reference for the top 30 Claim Adjustment Reason Codes by industry frequency in 2026. Description, payer concentration, prevention recommendation, and overturn likelihood per code. Plus the prevent-vs-overturn decision framework and how to triage the daily denial queue.

Top 30CARC codes 41%Avg overturn rate X12Standard maintained Updated2026 Edition

What CARC codes are, and why this list mattersThe denial story starts here.

Claim Adjustment Reason Codes, known as CARC codes, are the X12 standard codes payers attach to claim lines in the 835 remittance to explain why the line was paid less than billed, denied, or adjusted. They are the first signal a billing team has of a payment problem, and they are the input to every denial workflow, every prevention project, and every appeal decision. The list is maintained by the X12 standards committee and updated regularly. A working knowledge of the top CARCs is one of the highest-leverage skills in revenue cycle.

This article is the reference we wish every new denial analyst was handed on day one. It covers the top 30 CARCs by industry frequency in 2026, the payer concentration on each, the prevention recommendation we use in production, and the overturn likelihood when the denial is appealed. Bookmark this page. Print it. Hand it to a new hire.

Every CARC is a story. The smart denial team treats the CARC as the first sentence of the story, not the last. The next move is always to read the chart and the auth, not to file the appeal.

Industry frequency

Top CARCs by denial volume.

Approximate industry frequency of the top denial CARCs across a mixed payer book. The top eight CARCs account for roughly 70 percent of all denials. Prevention investment should follow the frequency, not the noise.

CARC 16

Lacks information for adjudication

18.4%

CARC 197

Precertification or authorization absent

14.3%

CARC 109

Claim not covered by this payer

11.1%

CARC 18

Exact duplicate claim/service

7.6%

CARC 96

Non-covered charge(s)

6.8%

CARC 11

Diagnosis inconsistent with procedure

5.6%

CARC 50

Not deemed medically necessary

4.5%

CARC 27

Expenses after coverage terminated

3.4%

The reference · top 30 CARCs

Description, payer, prevention, overturn.

Each row contains the CARC code, the official short description, the payer category where it concentrates, the prevention recommendation we use in production, and the typical overturn rate on appeal. H is high (above 60%), M is medium (30-60%), L is low (under 30%).

Code	Description	Payer focus	Prevention	Overturn
16	Claim lacks information needed for adjudication	All payers	Pre-submission validator checks claim-line modifiers, units, place of service, and attachments against payer rule pack.	M
18	Exact duplicate claim or service	All payers	Claim-level duplicate check against last 180 days before submission. Most CARC 18s are not appealable.	L
22	Care may be covered by another payer (COB)	Medicare, commercial	Coordination-of-benefits check at intake. Run secondary verification weekly for chronic patients.	M
23	Prior payer adjustment impact	Commercial secondary	Bill secondary with primary EOB attached at first submission. Pull from primary 835.	M
27	Expenses incurred after coverage terminated	Commercial	Real-time eligibility at every visit. Catch term date at intake.	L
29	Time limit for filing has expired	All payers	Claim-aging alert at 80 percent of payer timely-filing window. Track per-payer.	L
45	Charge exceeds fee schedule or contracted rate	Commercial	Contracted-rate library applied at charge entry. Match to payer fee schedule before submission.	L
50	Service not deemed a medical necessity	Medicare, MA	LCD and NCD policy check pre-submission. Documentation of medical necessity in chart at time of service.	M
96	Non-covered charges	All payers	Benefit-coverage check at intake. ABN signed for Medicare non-covered services.	L
97	Benefit included in another service	All payers	NCCI edit and bundling rules applied at coding. Modifier 59 only with documentation support.	M
109	Claim/service not covered by this payer/contractor	All payers	Real-time eligibility and active-coverage check. Coordination of benefits at intake.	M
119	Benefit maximum has been reached	Commercial	Authorization tracker counting cumulative used units against annual benefit cap.	L
125	Submission/billing errors	All payers	Pre-submission claim scrubber against payer companion guide. Field-level validation.	H
140	Patient/insured health identification number invalid	All payers	Eligibility verification at intake. Member-ID format check per payer rule pack.	H
151	Payment adjusted because info doesn't support volume	Medicare, MA	Time-based documentation in chart for time-billed codes. Units validated against duration.	M
167	Diagnosis not covered	Medicare, MA	LCD diagnosis-list check at coding. CMS coverage-determination cross-walk.	M
170	Payment denied when performed by this provider type	Medicare, Medicaid	Provider-type-to-code validity check at coding. Scope-of-practice rules per state.	M
171	Payment denied when furnished by this type of facility	All payers	Place-of-service-to-code validity check at coding. Site-of-service edits.	M
181	Procedure code was invalid on DOS	All payers	CPT and HCPCS validity check by date of service against active code set.	H
197	Precertification, authorization, or notification absent	Commercial, MA	Authorization tracker linking auth number, units, date span, service codes to claim at submission.	L
198	Precertification/authorization exceeded	Commercial, MA	Authorization balance counter. Trigger reauth at 80 percent of authorized units.	L
204	Service not covered under patient's current benefit plan	Commercial	Benefit verification at intake. Plan-level coverage check before scheduling.	L
252	Attachment/documentation required	All payers	Attachment automation per payer rule. Auto-attach chart notes for codes requiring documentation.	H
B7	Provider not certified/eligible for this procedure	Medicare, Medicaid	Credentialing-status check at coding. Provider effective dates per payer.	M
B9	Patient enrolled in a hospice	Medicare	Medicare CWF check at intake. Hospice election status query.	L
B11	Claim/service denied because procedure/treatment is deemed experimental/investigational	Commercial, MA	Payer experimental-list check at scheduling. Pre-auth documenting clinical necessity.	M
11	Diagnosis inconsistent with the procedure	All payers	DX-to-CPT validity check at coding. NCCI edit table applied.	H
4	Procedure code inconsistent with modifier or required modifier missing	All payers	Modifier validation per CPT and per payer at coding. Missing-modifier auto-flag.	H
5	Procedure code inconsistent with place of service	All payers	CPT-to-POS validity check at claim build. POS rule pack per payer.	H
15	Authorization number missing, invalid, or does not apply	Commercial, MA	Authorization tracker pre-populates auth number on every claim line by service and date span.	M
200	Expenses incurred during lapse in coverage	Commercial	Real-time eligibility verification at every visit. COB rerun monthly.	L

The decision framework

Prevent first. Overturn second.

Prevent

Prevention is where the dollars are.

Every prevented denial is worth roughly 4 to 6 times more than an overturned one. The math is simple: no rework labor, no appeal labor, no aged AR, no write-off risk. The investment goes into the data layer at intake, coding, and pre-submission.

Real-time eligibility at every visit, not at first visit only.
Authorization tracker linking auth to claim at submission.
Pre-submission claim scrubber against payer companion guide.
NCCI, LCD, and NCD edit library applied at coding.
Modifier rule pack per CPT per payer.
Attachment automation for documentation-required codes.

Overturn

Overturn the ones worth working.

Not every denial is worth appealing. Triage by dollar value first, then by CARC overturn likelihood, then by payer responsiveness. The daily denial queue should auto-rank by expected recovery dollars. Low-dollar, low-overturn CARCs should be batched and aged out unless the volume is large enough to justify a focused prevention project.

High-dollar plus high-overturn CARCs to the front of the queue.
CARC 197 and 27 rarely overturn; do not waste cycles on standard appeal.
CARC 11, 4, 5 overturn at 60 to 80 percent when the chart supports the code.
Payer-specific appeal templates with clinical attachment, not a form letter.
Track per-payer turnaround time on appeals and escalate slow ones.
Feed overturn data back into the prevention layer to update rule packs.

How to triage the daily denial queueThe triage stack has four layers.

A denial queue without triage is a denial queue that quietly loses money. The team works the loudest denials, not the highest-value ones. The fix is a four-layer triage stack applied automatically at the moment the 835 lands.

Layer one: dollar-value sort

The first cut is dollar value. Denials above a threshold (often $500 per line) go to the daily queue regardless of CARC. Denials between $100 and $500 enter a batch queue worked twice weekly. Denials under $100 are batched, reviewed weekly for prevention patterns, and most are written off after the second touch.

Layer two: CARC overturn rate

Within each dollar tier, sort by CARC overturn rate. The 60-percent-plus CARCs work first. The under-30 percent CARCs are sent to prevention review rather than appeal because the appeal-labor cost typically exceeds the recovery.

Layer three: payer responsiveness

Payers vary widely on appeal turnaround time and overturn behavior. Track per-payer history. Payers with two-week turnaround and 70 percent overturn rate get appealed immediately. Payers with 90-day turnaround and 30 percent overturn rate get appealed in batch with stronger documentation.

Layer four: prevention feedback

Every overturned denial is data. The appeal narrative, the clinical attachment, and the payer response feed back into the rule pack tuning. The CARC frequency report rerun monthly should show the top CARCs declining quarter over quarter. If they are not, the prevention layer is not working and the team is stuck appealing the same denials twice.

Frequently asked questions.

What is a CARC code?

CARC stands for Claim Adjustment Reason Code. It is the standard X12 code used by payers in the 835 remittance to explain why a claim line was paid less than billed, denied, or adjusted. CARC codes are paired with RARC codes (Remittance Advice Remark Codes) that provide additional context. The CARC list is maintained by the X12 standards committee.

What are the top denial CARC codes in 2026?

By industry frequency, the top denial CARC codes in 2026 are CARC 16 (lacks information for adjudication), CARC 197 (precertification or authorization absent), CARC 109 (claim not covered by this payer), CARC 18 (exact duplicate), CARC 96 (non-covered charges), CARC 11 (diagnosis inconsistent with procedure), CARC 50 (non-covered services not deemed medically necessary), and CARC 27 (expenses incurred after coverage terminated).

How do I prevent CARC 16 denials?

CARC 16 (lacks information for adjudication) is almost always a documentation or claim-data completeness problem. Prevention requires a pre-submission validator that checks claim-line modifiers, units, place of service, and attached documentation against payer-specific rule packs. The validator catches the gap before submission, not after denial.

How do I prevent CARC 197 denials?

CARC 197 (precertification or authorization absent) is a workflow failure between auth and claim. Prevention requires an authorization tracker that links the auth number, the authorized units, the date span, and the service codes to the claim at submission. Missing or expired auth blocks the claim from going out.

How do I prevent CARC 109 denials?

CARC 109 (claim not covered by this payer) usually means the patient changed coverage or the wrong payer was billed. Prevention is real-time eligibility at every visit, plus a coordination-of-benefits check at the time of service. Catching coverage changes at intake is cheaper than working a CARC 109 at appeal.

What is the difference between CARC and RARC?

CARC explains the reason for the payment adjustment. RARC adds context, either narrative or further explanation. A claim line can have one or more CARC codes and zero or more RARC codes attached. The pair tells the full story; reading only the CARC misses payer-specific context the RARC carries.

What overturn rate should I expect on appeal?

Industry average overturn rate across all CARC codes is approximately 41 percent. CARC-by-CARC variance is large. CARC 197 (auth absent) overturns at around 28 percent because the underlying problem cannot be fixed on appeal. CARC 11 (DX inconsistent with procedure) overturns at over 70 percent when the chart genuinely supports the code. Triage by CARC, payer, and dollar value.

How should I prioritize denial work by CARC?

Triage by dollar value first, then by CARC overturn likelihood, then by payer. High-dollar, high-overturn CARCs from your top three payers should land in the daily denial queue. Low-dollar, low-overturn CARCs should be batched and aged out unless the volume is large enough to justify a focused prevention project.

Want your top 30 CARCs mapped to prevention?

A free 30-day denial audit on your real 835 data. Under a same-day BAA. The output is a four-page report covering your top CARCs by dollar value, overturn likelihood, and a prevention roadmap tied to specific rule-pack changes. A senior partner on the call.

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