Official X12 description
“Claim/service lacks information or has submission/billing error(s).”
Source: X12 Claim Adjustment Reason Codes. The X12 External Code Lists are the single authoritative source for every CARC descriptor — always verify against the current release before building a claim-scrub rule.
What CARC 16 actually means
CARC 16 is the industry's most common catch-all denial: the claim is technically incomplete or contains a data error that prevents adjudication. The specific problem is almost always spelled out in the accompanying RARC(s) — if the 835 carries CARC 16 alone with no RARC, rework is blind. Examples include a missing referring provider NPI, an invalid place-of-service code, a blank accident indicator, or a missing required claim attachment. Correct the error and rebill; true appeal is rarely necessary.
Common root causes
- Missing or invalid NPI (rendering, referring, billing, or supervising).
- Place-of-service code missing or incompatible with the procedure.
- Missing required attachment (operative note, invoice for unlisted codes, anesthesia time).
- Patient demographic mismatch (DOB, gender, member ID) between the claim and the payer's eligibility file.
- Accident-related or third-party liability indicators missing when required.
Prevention checklist
- Enforce required-field validation at the scrubber level, keyed off payer-specific companion guides.
- Automate eligibility re-verification within 48 hours of service to catch demographic drift.
- Build payer-specific attachment rules (e.g., Medicare requires PWK segments for certain claims) into claim generation.
- Track CARC 16 by reason substring in your denials dashboard; any sudden spike usually indicates a payer companion-guide change.
Appeal strategy — step by step
Most CARC 16 denials clear faster with the right remediation than with a formal appeal. Work the steps in order and escalate only when a lower-effort path has been ruled out.
- 1Read the accompanying RARC carefully — the RARC tells you exactly what is missing. If none is present, call the payer for clarification before working the denial.
- 2For most CARC 16 denials, submit a corrected claim (frequency code 7) with the missing data rather than a formal appeal.
- 3When the payer loses an attachment that was genuinely submitted, include the original clearinghouse tracking number and the PWK segment detail in the resubmission.
Sample appeal-letter language for CARC 16
[Provider letterhead]
Re: Appeal of CARC 16 — Claim #{claim_number}
Member: {member_name} · Member ID: {member_id}
Date(s) of Service: {dos}
On {remittance_date} this claim was adjusted with CARC 16:
"Claim/service lacks information or has submission/billing error(s)."
We respectfully request reconsideration. The X12 External Code List
definition of CARC 16 does not apply to this claim for the
following reasons:
1. [Cite the clinical / coding / policy fact that rebuts the adjustment]
2. [Cite the supporting documentation attached — op note, EOB,
LCD/NCD citation, NCCI edit indicator, modifier rationale]
3. [Cite the payer's own policy where applicable]
Attached: {list supporting documents}
Please process payment under the member's benefits. If additional
information is required, contact the billing office at
{provider_phone} or {provider_email}.
Sincerely,
{billing_manager_name}, {credentials}
Edit the bracketed fields before sending. This template is a starting point; a payer-specific appeal form may still be required — check the provider portal first.
Payer-specific notes
Payer-specific behavior for CARC 16 publishes here as the QuickIntell anonymized denial ETL ingests sufficient volume. In the meantime, consult the payer directory for the relevant provider manual and appeal form.
How common is CARC 16?
Search demand rank
#1
Out of 306 seeded CARCs, ranked by combined US monthly search volume for "CARC 16", "CO-16 denial", and "denial code 16".
Platform frequency
Pending ETL
Platform frequency ranks publish once the anonymized denial-rate pipeline reaches the publication threshold (strategy §12 Phase 2).
How QuickRCM prevents CARC 16
QuickRCM catches the root causes above before the 837 leaves the clearinghouse:
- Claim-scrub rules fire on every root cause listed above — the scrub references the same X12 CAS segment logic that drives the denial, so what the payer checks, QuickRCM checks first.
- When a denial lands, QuickRCM routes it to the correct worker with the documentation bundle already attached (op note, LCD citation, modifier rationale, EOB, primary 835).
- Appeal templates tuned to each CARC (including this one) pull the supporting facts from the claim and fill the bracketed fields automatically.
CAQH CORE code combinations for CARC 16
Under the CAQH CORE Payment and Remittance Uniform Use rule, health plans may pair CARC 16 only with the remark codes and group codes below for the defined business scenario 2 (Missing, invalid or incomplete data from the submitted claim). A combination outside this list on an 835 is itself a payer compliance issue worth raising.
| RARC | Remark description | Group code | Scenario |
|---|---|---|---|
| M12 | Diagnostic tests performed by a physician must indicate whether purchased services are included on the claim. | CO or PI | 2 |
| M20 | Missing/incomplete/invalid HCPCS. | CO or PI | 2 |
| M21 | Missing/incomplete/invalid place of residence for this service/item provided in a home. | CO or PI | 2 |
| M22 | Missing/incomplete/invalid number of miles traveled. | CO or PI | 2 |
| M24 | Missing/incomplete/invalid number of doses per vial. | CO or PI | 2 |
| M44 | Missing/incomplete/invalid condition code. | CO or PI | 2 |
| M45 | Missing/incomplete/invalid occurrence code(s). | CO or PI | 2 |
| M46 | Missing/incomplete/invalid occurrence span code(s). | CO or PI | 2 |
| M47 | Missing/incomplete/invalid Payer Claim Control Number. Other terms exist for this element including, but not limited to, Internal Control Number (ICN), Claim Control Number (CCN), Document Control Number (DCN). | CO or PI | 2 |
| M49 | Missing/incomplete/invalid value code(s) or amount(s). | CO or PI | 2 |
| M50 | Missing/incomplete/invalid revenue code(s). | CO or PI | 2 |
| M51 | Missing/incomplete/invalid procedure code(s). | CO or PI | 2 |
| M52 | Missing/incomplete/invalid "from" date(s) of service. | CO or PI | 2 |
| M53 | Missing/incomplete/invalid days or units of service. | CO or PI | 2 |
| M54 | Missing/incomplete/invalid total charges. | CO or PI | 2 |
| M56 | Missing/incomplete/invalid payer identifier. | CO or PI | 2 |
| M59 | Missing/incomplete/invalid "to" date(s) of service. | CO or PI | 2 |
| M60 | Missing Certificate of Medical Necessity. | CO or PI | 2 |
| M62 | Missing/incomplete/invalid treatment authorization code. | CO or PI | 2 |
| M64 | Missing/incomplete/invalid other diagnosis. | CO or PI | 2 |
| M65 | One interpreting physician charge can be submitted per claim when a purchased diagnostic test is indicated. Please submit a separate claim for each interpreting physician. | CO or PI | 2 |
| M66 | Our records indicate that you billed diagnostic tests subject to price limitations and the procedure code submitted includes a professional component. Only the technical component is subject to price limitations. Please submit the technical and professional components of this service as separate line items. | CO or PI | 2 |
| M67 | Missing/incomplete/invalid other procedure code(s). | CO or PI | 2 |
| M73 | The HPSA/Physician Scarcity bonus can only be paid on the professional component of this service. Rebill as separate professional and technical components. | CO or PI | 2 |
| M76 | Missing/incomplete/invalid diagnosis or condition. | CO or PI | 2 |
| M77 | Missing/incomplete/invalid/inappropriate place of service. | CO or PI | 2 |
| M79 | Missing/incomplete/invalid charge. | CO or PI | 2 |
| M81 | You are required to code to the highest level of specificity. | CO or PI | 2 |
| M84 | Medical code sets used must be the codes in effect at the time of service. | CO or PI | 2 |
| M91 | Lab procedures with different CLIA certification numbers must be billed on separate claims. | CO or PI | 2 |
| M99 | Missing/incomplete/invalid Universal Product Number/Serial Number. | CO or PI | 2 |
| M119 | Missing/incomplete/invalid/ deactivated/withdrawn National Drug Code (NDC) | CO or PI | 2 |
| M122 | Missing/incomplete/invalid level of subluxation. | CO or PI | 2 |
| M123 | Missing/incomplete/invalid name, strength, or dosage of the drug furnished. | CO or PI | 2 |
| M124 | Missing indication of whether the patient owns the equipment that requires the part or supply. | CO or PI | 2 |
| M125 | Missing/incomplete/invalid information on the period of time for which the service/supply/equipment will be needed. | CO or PI | 2 |
| M126 | Missing/incomplete/invalid individual lab codes included in the test. | CO or PI | 2 |
| M129 | Missing/incomplete/invalid indicator of x‐ray availability for review. | CO or PI | 2 |
| M133 | Claim did not identify who performed the purchased diagnostic test or the amount you were charged for the test. | CO or PI | 2 |
| M136 | Missing/incomplete/invalid indication that the service was supervised or evaluated by a physician. | CO or PI | 2 |
| MA04 | Secondary payment cannot be considered without the identity of or payment information from the primary payer. The information was either not reported or was illegible. | CO or PI | 2 |
| MA21 | SSA records indicate mismatch with name and sex. | CO or PI | 2 |
| MA27 | Missing/incomplete/invalid entitlement number or name shown on the claim. | CO or PI | 2 |
| MA30 | Missing/incomplete/invalid type of bill. | CO or PI | 2 |
| MA31 | Missing/incomplete/invalid beginning and ending dates of the period billed. | CO or PI | 2 |
| MA32 | Missing/incomplete/invalid number of covered days during the billing period. | CO or PI | 2 |
| MA33 | Missing/incomplete/invalid non-covered days during the billing period. | CO or PI | 2 |
| MA34 | Missing/incomplete/invalid number of coinsurance days during the billing period. | CO or PI | 2 |
| MA35 | Missing/incomplete/invalid number of lifetime reserve days. | CO or PI | 2 |
| MA36 | Missing/incomplete/invalid patient name. | CO or PI | 2 |
| MA37 | Missing/incomplete/invalid patient's address. | CO or PI | 2 |
| MA39 | Missing/incomplete/invalid gender. | CO or PI | 2 |
| MA40 | Missing/incomplete/invalid admission date. | CO or PI | 2 |
| MA41 | Missing/incomplete/invalid admission type. | CO or PI | 2 |
| MA42 | Missing/incomplete/invalid admission source. | CO or PI | 2 |
| MA43 | Missing/incomplete/invalid patient status. | CO or PI | 2 |
| MA48 | Missing/incomplete/invalid name or address of responsible party or primary payer. | CO or PI | 2 |
| MA50 | Missing/incomplete/invalid Investigational Device Exemption number for FDA-approved clinical trial services. | CO or PI | 2 |
| MA53 | Missing/incomplete/invalid Competitive Bidding Demonstration Project identification. | CO or PI | 2 |
| MA58 | Missing/incomplete/invalid release of information indicator. | CO or PI | 2 |
| MA60 | Missing/incomplete/invalid patient relationship to insured. | CO or PI | 2 |
| MA61 | Missing/incomplete/invalid social security number. | CO or PI | 2 |
| MA63 | Missing/incomplete/invalid principal diagnosis. | CO or PI | 2 |
| MA64 | Our records indicate that we should be the third payer for this claim. We cannot process this claim until we have received payment information from the primary and secondary payers. | CO or PI | 2 |
| MA65 | Missing/incomplete/invalid admitting diagnosis. | CO or PI | 2 |
| MA66 | Missing/incomplete/invalid principal procedure code. | CO or PI | 2 |
| MA69 | Missing/incomplete/invalid remarks. | CO or PI | 2 |
| MA70 | Missing/incomplete/invalid provider representative signature. | CO or PI | 2 |
| MA71 | Missing/incomplete/invalid provider representative signature date. | CO or PI | 2 |
| MA75 | Missing/incomplete/invalid patient or authorized representative signature. | CO or PI | 2 |
| MA76 | Missing/incomplete/invalid provider identifier for home health agency or hospice when physician is performing care plan oversight services. | CO or PI | 2 |
| MA81 | Missing/incomplete/invalid provider/supplier signature. | CO or PI | 2 |
| MA83 | Did not indicate whether we are the primary or secondary payer. | CO or PI | 2 |
| MA88 | Missing/incomplete/invalid insured's address and/or telephone number for the primary payer. | CO or PI | 2 |
| MA89 | Missing/incomplete/invalid patient's relationship to the insured for the primary payer. | CO or PI | 2 |
| MA90 | Missing/incomplete/invalid employment status code for the primary insured. | CO or PI | 2 |
| MA92 | Missing plan information for other insurance. | CO or PI | 2 |
| MA94 | Did not enter the statement "Attending physician not hospice employee" on the claim form to certify that the rendering physician is not an employee of the hospice. | CO or PI | 2 |
| MA96 | Claim rejected. Coded as a Medicare Managed Care Demonstration but patient is not enrolled in a Medicare managed care plan. | CO or PI | 2 |
| MA97 | Missing/incomplete/invalid Medicare Managed Care Demonstration contract number or clinical trial registry number. | CO or PI | 2 |
| MA99 | Missing/incomplete/invalid Medigap information. | CO or PI | 2 |
| MA100 | Missing/incomplete/invalid date of current illness or symptoms. | CO or PI | 2 |
| MA110 | Missing/incomplete/invalid information on whether the diagnostic test(s) were performed by an outside entity or if no purchased tests are included on the claim. | CO or PI | 2 |
| MA111 | Missing/incomplete/invalid purchase price of the test(s) and/or the performing laboratory's name and address. | CO or PI | 2 |
| MA112 | Missing/incomplete/invalid group practice information. | CO or PI | 2 |
| MA113 | Incomplete/invalid taxpayer identification number (TIN) submitted by you per the Internal Revenue Service. Your claims cannot be processed without your correct TIN, and you may not bill the patient pending correction of your TIN. There are no appeal rights for unprocessable claims, but you may resubmit this claim after you have notified this office of your correct TIN. | CO or PI | 2 |
| MA114 | Missing/incomplete/invalid information on where the services were furnished. | CO or PI | 2 |
| MA115 | Missing/incomplete/invalid physical location (name and address, or PIN) where the service(s) were rendered in a Health Professional Shortage Area (HPSA). | CO or PI | 2 |
| MA116 | Did not complete the statement 'Homebound' on the claim to validate whether laboratory services were performed at home or in an institution. | CO or PI | 2 |
| MA120 | Missing/incomplete/invalid CLIA certification number. | CO or PI | 2 |
| MA121 | Missing/incomplete/invalid x‐ray date. | CO or PI | 2 |
| MA122 | Missing/incomplete/invalid initial treatment date. | CO or PI | 2 |
| MA128 | Missing/incomplete/invalid FDA approval number. | CO or PI | 2 |
| MA134 | Missing/incomplete/invalid provider number of the facility where the patient resides. | CO or PI | 2 |
| N4 | Missing/Incomplete/Invalid prior Insurance Carrier(s) EOB. | CO or PI | 2 |
| N8 | Crossover claim denied by previous payer and complete claim data not forwarded. Resubmit this claim to this payer to provide adequate data for adjudication. | CO or PI | 2 |
| N27 | Missing/incomplete/invalid treatment number. | CO or PI | 2 |
| N31 | Missing/incomplete/invalid prescribing provider identifier. | CO or PI | 2 |
| N32 | Claim must be submitted by the provider who rendered the service. | CO or PI | 2 |
| N34 | Incorrect claim form/format for this service. | CO or PI | 2 |
| N37 | Missing/incomplete/invalid tooth number/letter. | CO or PI | 2 |
| N39 | Procedure code is not compatible with tooth number/letter. | CO or PI | 2 |
| N46 | Missing/incomplete/invalid admission hour. | CO or PI | 2 |
| N48 | Claim information does not agree with information received from other insurance carrier. | CO or PI | 2 |
| N50 | Missing/incomplete/invalid discharge information. | CO or PI | 2 |
| N53 | Missing/incomplete/invalid point of pick‐up address. | CO or PI | 2 |
| N54 | Claim information is inconsistent with pre-certified/authorized services. | CO or PI | 2 |
| N56 | Procedure code billed is not correct/valid for the services billed or the date of service billed. | CO or PI | 2 |
| N57 | Missing/incomplete/invalid prescribing date. | CO or PI | 2 |
| N58 | Missing/incomplete/invalid patient liability amount. | CO or PI | 2 |
| N61 | Rebill services on separate claims. | CO or PI | 2 |
| N62 | Dates of service span multiple rate periods. Resubmit separate claims. | CO or PI | 2 |
| N63 | Rebill services on separate claim lines. | CO or PI | 2 |
| N64 | The "from" and "to" dates must be different. | CO or PI | 2 |
| N65 | Procedure code or procedure rate count cannot be determined, or was not on file, for the date of service/provider. | CO or PI | 2 |
| N75 | Missing/incomplete/invalid tooth surface information. | CO or PI | 2 |
| N76 | Missing/incomplete/invalid number of riders. | CO or PI | 2 |
| N77 | Missing/incomplete/invalid designated provider number. | CO or PI | 2 |
| N80 | Missing/incomplete/invalid prenatal screening information. | CO or PI | 2 |
| N81 | Procedure billed is not compatible with tooth surface code. | CO or PI | 2 |
| N93 | A separate claim must be submitted for each place of service. Services furnished at multiple sites may not be billed in the same claim. | CO or PI | 2 |
| N94 | Claim/Service denied because a more specific taxonomy code is required for adjudication. | CO or PI | 2 |
| N142 | The original claim was denied. Resubmit a new claim, not a replacement claim. | CO or PI | 2 |
| N147 | Long term care case mix or per diem rate cannot be determined because the patient ID number is missing, incomplete, or invalid on the assignment request. | CO or PI | 2 |
| N148 | Missing/incomplete/invalid date of last menstrual period. | CO or PI | 2 |
| N150 | Missing/incomplete/invalid model number. | CO or PI | 2 |
| N152 | Missing/incomplete/invalid replacement claim information. | CO or PI | 2 |
| N153 | Missing/incomplete/invalid room and board rate. | CO or PI | 2 |
| N163 | Medical record does not support code billed per the code definition. | CO or PI | 2 |
| N173 | No qualifying hospital stay dates were provided for this episode of care. | CO or PI | 2 |
| N182 | This claim/service must be billed according to the schedule for this plan. | CO or PI | 2 |
| N184 | Rebill technical and professional components separately. | CO or PI | 2 |
| N188 | The approved level of care does not match the procedure code submitted. | CO or PI | 2 |
| N190 | Missing contract indicator. | CO or PI | 2 |
| N203 | Missing/incomplete/invalid anesthesia time/units. | CO or PI | 2 |
| N206 | The supporting documentation does not match the information sent on the claim. | CO or PI | 2 |
| N207 | Missing/incomplete/invalid weight. | CO or PI | 2 |
| N208 | Missing/incomplete/invalid DRG code. | CO or PI | 2 |
| N209 | Missing/incomplete/invalid taxpayer identification number (TIN). | CO or PI | 2 |
| N213 | Missing/incomplete/invalid facility/discrete unit DRG/DRG exempt status information. | CO or PI | 2 |
| N229 | Incomplete/invalid contract indicator. | CO or PI | 2 |
| N230 | Incomplete/invalid indication of whether the patient owns the equipment that requires the part or supply. | CO or PI | 2 |
| N245 | Incomplete/invalid plan information for other insurance. | CO or PI | 2 |
| N247 | Missing/incomplete/invalid assistant surgeon taxonomy. | CO or PI | 2 |
| N248 | Missing/incomplete/invalid assistant surgeon name. | CO or PI | 2 |
| N249 | Missing/incomplete/invalid assistant surgeon primary identifier. | CO or PI | 2 |
| N250 | Missing/incomplete/invalid assistant surgeon secondary identifier. | CO or PI | 2 |
| N251 | Missing/incomplete/invalid attending provider taxonomy. | CO or PI | 2 |
| N252 | Missing/incomplete/invalid attending provider name. | CO or PI | 2 |
| N253 | Missing/incomplete/invalid attending provider primary identifier. | CO or PI | 2 |
| N254 | Missing/incomplete/invalid attending provider secondary identifier. | CO or PI | 2 |
| N255 | Missing/incomplete/invalid billing provider taxonomy. | CO or PI | 2 |
| N256 | Missing/incomplete/invalid billing provider/supplier name. | CO or PI | 2 |
| N257 | Missing/incomplete/invalid billing provider/supplier primary identifier. | CO or PI | 2 |
| N258 | Missing/incomplete/invalid billing provider/supplier address. | CO or PI | 2 |
| N259 | Missing/incomplete/invalid billing provider/supplier secondary identifier. | CO or PI | 2 |
| N260 | Missing/incomplete/invalid billing provider/supplier contact information. | CO or PI | 2 |
| N261 | Missing/incomplete/invalid operating provider name. | CO or PI | 2 |
| N262 | Missing/incomplete/invalid operating provider primary identifier. | CO or PI | 2 |
| N263 | Missing/incomplete/invalid operating provider secondary identifier. | CO or PI | 2 |
| N264 | Missing/incomplete/invalid ordering provider name. | CO or PI | 2 |
| N265 | Missing/incomplete/invalid ordering provider primary identifier. | CO or PI | 2 |
| N266 | Missing/incomplete/invalid ordering provider address. | CO or PI | 2 |
| N267 | Missing/incomplete/invalid ordering provider secondary identifier. | CO or PI | 2 |
| N268 | Missing/incomplete/invalid ordering provider contact information. | CO or PI | 2 |
| N269 | Missing/incomplete/invalid other provider name. | CO or PI | 2 |
| N270 | Missing/incomplete/invalid other provider primary identifier. | CO or PI | 2 |
| N271 | Missing/incomplete/invalid other provider secondary identifier. | CO or PI | 2 |
| N272 | Missing/incomplete/invalid other payer attending provider identifier. | CO or PI | 2 |
| N273 | Missing/incomplete/invalid other payer operating provider identifier. | CO or PI | 2 |
| N274 | Missing/incomplete/invalid other payer other provider identifier. | CO or PI | 2 |
| N275 | Missing/incomplete/invalid other payer purchased service provider identifier. | CO or PI | 2 |
| N276 | Missing/incomplete/invalid other payer referring provider identifier. | CO or PI | 2 |
| N277 | Missing/incomplete/invalid other payer rendering provider identifier. | CO or PI | 2 |
| N278 | Missing/incomplete/invalid other payer service facility provider identifier. | CO or PI | 2 |
| N279 | Missing/incomplete/invalid pay-to provider name. | CO or PI | 2 |
| N280 | Missing/incomplete/invalid pay-to provider primary identifier. | CO or PI | 2 |
| N281 | Missing/incomplete/invalid pay-to provider address. | CO or PI | 2 |
| N282 | Missing/incomplete/invalid pay-to provider secondary identifier. | CO or PI | 2 |
| N283 | Missing/incomplete/invalid purchased service provider identifier. | CO or PI | 2 |
| N284 | Missing/incomplete/invalid referring provider taxonomy. | CO or PI | 2 |
| N285 | Missing/incomplete/invalid referring provider name. | CO or PI | 2 |
| N286 | Missing/incomplete/invalid referring provider primary identifier. | CO or PI | 2 |
| N287 | Missing/incomplete/invalid referring provider secondary identifier. | CO or PI | 2 |
| N288 | Missing/incomplete/invalid rendering provider taxonomy. | CO or PI | 2 |
| N289 | Missing/incomplete/invalid rendering provider name. | CO or PI | 2 |
| N290 | Missing/incomplete/invalid rendering provider primary identifier. | CO or PI | 2 |
| N291 | Missing/incomplete/invalid rendering provider secondary identifier. | CO or PI | 2 |
| N292 | Missing/incomplete/invalid service facility name. | CO or PI | 2 |
| N293 | Missing/incomplete/invalid service facility primary identifier. | CO or PI | 2 |
| N294 | Missing/incomplete/invalid service facility primary address. | CO or PI | 2 |
| N295 | Missing/incomplete/invalid service facility secondary identifier. | CO or PI | 2 |
| N296 | Missing/incomplete/invalid supervising provider name. | CO or PI | 2 |
| N297 | Missing/incomplete/invalid supervising provider primary identifier. | CO or PI | 2 |
| N298 | Missing/incomplete/invalid supervising provider secondary identifier. | CO or PI | 2 |
| N299 | Missing/incomplete/invalid occurrence date(s). | CO or PI | 2 |
| N300 | Missing/incomplete/invalid occurrence span date(s). | CO or PI | 2 |
| N301 | Missing/incomplete/invalid procedure date(s). | CO or PI | 2 |
| N302 | Missing/incomplete/invalid other procedure date(s). | CO or PI | 2 |
| N303 | Missing/incomplete/invalid principal procedure date. | CO or PI | 2 |
| N304 | Missing/incomplete/invalid dispensed date. | CO or PI | 2 |
| N305 | Missing/incomplete/invalid injury/accident date. | CO or PI | 2 |
| N306 | Missing/incomplete/invalid acute manifestation date. | CO or PI | 2 |
| N307 | Missing/incomplete/invalid adjudication or payment date. | CO or PI | 2 |
| N308 | Missing/incomplete/invalid appliance placement date. | CO or PI | 2 |
| N309 | Missing/incomplete/invalid assessment date. | CO or PI | 2 |
| N310 | Missing/incomplete/invalid assumed or relinquished care date. | CO or PI | 2 |
| N312 | Missing/incomplete/invalid begin therapy date. | CO or PI | 2 |
| N313 | Missing/incomplete/invalid certification revision date. | CO or PI | 2 |
| N314 | Missing/incomplete/invalid diagnosis date. | CO or PI | 2 |
| N315 | Missing/incomplete/invalid disability from date. | CO or PI | 2 |
| N316 | Missing/incomplete/invalid disability to date. | CO or PI | 2 |
| N317 | Missing/incomplete/invalid discharge hour. | CO or PI | 2 |
| N318 | Missing/incomplete/invalid discharge or end of care date. | CO or PI | 2 |
| N319 | Missing/incomplete/invalid hearing or vision prescription date. | CO or PI | 2 |
| N320 | Missing/incomplete/invalid Home Health Certification Period. | CO or PI | 2 |
| N321 | Missing/incomplete/invalid last admission period. | CO or PI | 2 |
| N322 | Missing/incomplete/invalid last certification date. | CO or PI | 2 |
| N323 | Missing/incomplete/invalid last contact date. | CO or PI | 2 |
| N324 | Missing/incomplete/invalid last seen/visit date. | CO or PI | 2 |
| N325 | Missing/incomplete/invalid last worked date. | CO or PI | 2 |
| N326 | Missing/incomplete/invalid last x‐ray date. | CO or PI | 2 |
| N327 | Missing/incomplete/invalid other insured birth date. | CO or PI | 2 |
| N328 | Missing/incomplete/invalid Oxygen Saturation Test date. | CO or PI | 2 |
| N329 | Missing/incomplete/invalid patient birth date. | CO or PI | 2 |
| N330 | Missing/incomplete/invalid patient death date. | CO or PI | 2 |
| N331 | Missing/incomplete/invalid physician order date. | CO or PI | 2 |
| N332 | Missing/incomplete/invalid prior hospital discharge date. | CO or PI | 2 |
| N333 | Missing/incomplete/invalid prior placement date. | CO or PI | 2 |
| N334 | Missing/incomplete/invalid re-evaluation date. | CO or PI | 2 |
| N335 | Missing/incomplete/invalid referral date. | CO or PI | 2 |
| N336 | Missing/incomplete/invalid replacement date. | CO or PI | 2 |
| N337 | Missing/incomplete/invalid secondary diagnosis date. | CO or PI | 2 |
| N338 | Missing/incomplete/invalid shipped date. | CO or PI | 2 |
| N339 | Missing/incomplete/invalid similar illness or symptom date. | CO or PI | 2 |
| N340 | Missing/incomplete/invalid subscriber birth date. | CO or PI | 2 |
| N341 | Missing/incomplete/invalid surgery date. | CO or PI | 2 |
| N342 | Missing/incomplete/invalid test performed date. | CO or PI | 2 |
| N343 | Missing/incomplete/invalid Transcutaneous Electrical Nerve Stimulator (TENS) trial start date. | CO or PI | 2 |
| N344 | Missing/incomplete/invalid Transcutaneous Electrical Nerve Stimulator (TENS) trial end date. | CO or PI | 2 |
| N345 | Date range not valid with units submitted. | CO or PI | 2 |
| N346 | Missing/incomplete/invalid oral cavity designation code. | CO or PI | 2 |
| N349 | The administration method and drug must be reported to adjudicate this service. | CO or PI | 2 |
| N350 | Missing/incomplete/invalid description of service for a Not Otherwise Classified (NOC) code or for an Unlisted/By Report procedure. | CO or PI | 2 |
| N359 | Missing/incomplete/invalid height. | CO or PI | 2 |
| N374 | Primary Medicare Part A insurance has been exhausted and a Part B Remittance Advice is required. | CO or PI | 2 |
| N378 | Missing/incomplete/invalid prescription quantity. | CO or PI | 2 |
| N382 | Missing/incomplete/invalid patient identifier. | CO or PI | 2 |
| N384 | Records indicate that the referenced body part/tooth has been removed in a previous procedure. | CO or PI | 2 |
| N388 | Missing/incomplete/invalid prescription number. | CO or PI | 2 |
| N389 | Duplicate prescription number submitted. | CO or PI | 2 |
| N407 | You are not an approved submitter for this transmission format. | CO or PI | 2 |
| N430 | Procedure code is inconsistent with the units billed. | CO or PI | 2 |
| N433 | Resubmit this claim using only your National Provider Identifier (NPI). | CO or PI | 2 |
| N434 | Missing/Incomplete/Invalid Present on Admission indicator. | CO or PI | 2 |
| N439 | Missing anesthesia physical status report/indicators. | CO or PI | 2 |
| N440 | Incomplete/invalid anesthesia physical status report/indicators. | CO or PI | 2 |
| N443 | Missing/incomplete/invalid total time or begin/end time. | CO or PI | 2 |
| N471 | Missing/incomplete/invalid HIPPS Rate Code. | CO or PI | 2 |
| N479 | Missing Explanation of Benefits (Coordination of Benefits or Medicare Secondary Payer). | CO or PI | 2 |
| N480 | Incomplete/invalid Explanation of Benefits (Coordination of Benefits or Medicare Secondary Payer). | CO or PI | 2 |
| N519 | Invalid combination of HCPCS modifiers. | CO or PI | 2 |
| N521 | Mismatch between the submitted provider information and the provider information stored in our system. | CO or PI | 2 |
| N541 | Mismatch between the submitted insurance type code and the information stored in our system. | CO or PI | 2 |
| N547 | A refund request (Frequency Type Code 8) was processed previously. | CO or PI | 2 |
| N554 | Missing/Incomplete/Invalid Family Planning Indicator. | CO or PI | 2 |
| N562 | The provider number of your incoming claim does not match the provider number on the processed Notice of Admission (NOA) for this bundled payment. | CO or PI | 2 |
| N572 | This procedure is not payable unless appropriate non-payable reporting codes and associated modifiers are submitted. | CO | 2 |
| N575 | Mismatch between the submitted ordering/referring provider name and the ordering/referring provider name stored in our records. | CO or PI | 2 |
| N595 | Records reflect the injured party did not complete an Assignment of Benefits for this loss. | CO or PI | 2 |
| N596 | Records reflect the injured party did not complete a Medical Authorization for this loss. | CO or PI | 2 |
| N625 | Missing/Incomplete/Invalid Workers' Compensation Claim Number. | CO or PI | 2 |
| N653 | The date of injury does not match the reported date of loss. | CO or PI | 2 |
| N657 | This should be billed with the appropriate code for these services. | CO or PI | 2 |
| N684 | Payment denied as this is a specialty claim submitted as a general claim. | CO or PI | 2 |
| N685 | Missing/Incomplete/Invalid Prosthesis, Crown or Inlay Code. | CO or PI | 2 |
| N752 | Missing/incomplete/invalid HIPPS Treatment Authorization Code (TAC). | CO or PI | 2 |
| N753 | Missing/incomplete/invalid Attachment Control Number. | CO or PI | 2 |
| N754 | Missing/incomplete/invalid Referring Provider or Other Source Qualifier on the 1500 Claim Form. | CO or PI | 2 |
| N755 | Missing/incomplete/invalid ICD Indicator. | CO or PI | 2 |
| N756 | Missing/incomplete/invalid point of drop-off address. | CO or PI | 2 |
| N763 | The demonstration code is not appropriate for this claim; resubmit without a demonstration code. | CO or PI | 2 |
| N764 | Missing/incomplete/invalid Hematocrit (HCT) value. | CO or PI | 2 |
| N769 | A lateral diagnosis is required. | CO or PI | 2 |
| N777 | Missing Assignment of Benefits Indicator. | CO or PI | 2 |
| N778 | Missing Primary Care Physician Information. | CO or PI | 2 |
| N779 | Replacement/Void claims cannot be submitted until the original claim has finalized. Please resubmit once payment or denial is received. | CO or PI | 2 |
| N780 | Missing/incomplete/invalid end therapy date. | CO or PI | 2 |
| N784 | Missing comprehensive procedure code. | CO or PI | 2 |
| N795 | Item must be resubmitted as a purchase. | CO or PI | 2 |
| N796 | Missing/incomplete/invalid Hemoglobin (Hb or Hgb) value. | CO or PI | 2 |
| N797 | Missing/incomplete/invalid date qualifier. | CO or PI | 2 |
| N798 | Submit a void request for the original claim and resubmit a new claim. | CO or PI | 2 |
| N799 | Submitted identifier must be an individual identifier, not group identifier. | CO or PI | 2 |
| N800 | Only one service date is allowed per claim. | CO or PI | 2 |
| N803 | Submission of the claim for the service rendered is the responsibility of the Contracted Medical Group or Hospital. | CO or PI | 2 |
| N811 | Missing Federal Sequestration Reduction from Prior Payer. | CO or PI | 2 |
| N812 | The start service date through and end service date cannot span greater than 18 months. | CO or PI | 2 |
| N815 | Missing/Incomplete/Invalid NCD Unit Count. | CO or PI | 2 |
| N816 | Missing/Incomplete/Invalid NCD Unit of Measure. | CO or PI | 2 |
| N818 | Claims Dates of Service do not match Electronic Visit Verification System. | CO or PI | 2 |
| N820 | Electronic Visit Verification System units do not meet requirements of visit. | CO or PI | 2 |
| N821 | Electronic Visit Verification System visit not found. | CO or PI | 2 |
| N822 | Missing Procedure Modifier(s). | CO or PI | 2 |
| N823 | Incomplete/Invalid Procedure modifier(s). | CO or PI | 2 |
| N827 | Missing/Incomplete/Invalid Federal Information Processing Standard (FIPS) Code. | CO or PI | 2 |
| N829 | Missing/incomplete/invalid Diagnostics Exchange Z-Code Identifier. | CO or PI | 2 |
| N832 | Duplicate occurrence code/occurrence span code. | CO or PI | 2 |
| N843 | Missing/incomplete/invalid Core-Based Statistical Area (CBSA) code. | CO or PI | 2 |
| N846 | National Drug Code (NDC) supplied does not correspond to the HCPCs/CPT billed. | CO or PI | 2 |
| N847 | National Drug Code (NDC) billed is obsolete. | CO or PI | 2 |
| N848 | National Drug Code (NDC) billed cannot be associated with a product. | CO or PI | 2 |
| N852 | The pay-to and rendering provider tax identification numbers (TINs) do not match | CO or PI | 2 |
| N890 | Electronic Visit Verification Data Element Requirements were not met | CO or PI | 2 |
| N892 | The claim does not meet the criteria for acceptable use of the Delay Reason Code | CO or PI | 2 |
| N898 | Missing/incomplete/invalid Resource Utilization Group(s) (RUG) code(s). | CO or PI | 2 |
Source: CAQH CORE-required Code Combinations v3.10.0 (2026-02).
The rule behind CARC 16
CARC 16 means the claim lacks information. On drug lines the usual gap is the NDC, its quantity or the unit conversion; the HCPCS drug pages carry the ASP crosswalk with billing units per package. On Medicare lab, imaging and DMEPOS claims, CARC 16 with N264 and N575 is an ordering practitioner name mismatch, and with N265 a missing ordering NPI.
Frequently asked questions — CARC 16
What does CARC 16 mean?
CARC 16 is an X12 Claim Adjustment Reason Code. The official definition is: "Claim/service lacks information or has submission/billing error(s)." In plain English, the payer is telling you cARC 16 is the industry's most common catch-all denial: the claim is technically incomplete or contains a data error that prevents adjudication. The specific problem is almost always spelled out in the accompanying RARC(s) — if the 835 carries CARC 16 alone with no RARC, rework is blind. Examples include a missing referring provider NPI, an invalid place-of-service code, a blank accident indicator, or a missing required claim attachment. Correct the error and rebill; true appeal is rarely necessary.
How do I resolve a CARC 16 (CO-16) denial?
Start with the most common root cause: Missing or invalid NPI (rendering, referring, billing, or supervising). First step: Read the accompanying RARC carefully — the RARC tells you exactly what is missing. If none is present, call the payer for clarification before working the denial. See the full remediation and appeal checklist on this page before filing a formal appeal.
Is CARC 16 patient responsibility?
No — CARC 16 is typically carried under CO (Contractual Obligation) or OA (Other Adjustment), which means it is the provider's responsibility, not the patient's. Do not bill the patient unless the 835 CAS group code is PR.
What does CARC 16 look like on an EOB or 835 remittance?
On the 835 ERA, CARC 16 appears in Loop 2110 CAS segment as "CAS*CO*16*{amount}". On a paper EOB the same code prints in the Adjustment/Denial Reason column with the X12 description: "Claim/service lacks information or has submission/billing error(s)." — usually paired with one or more RARC remark codes in the same remittance line for additional context.
Which RARC is paired with CARC 16?
CARC 16 is commonly observed with RARC M51, N4, N264. The RARC narrows the reason — for example, pointing at a missing modifier, an LCD citation, or a specific policy. Fix the underlying CARC first; the RARC usually clears with the corrected claim.
Disclaimer
This page is operational reference for medical-billing professionals. It is not legal, clinical, or contractual advice. X12 code descriptors are maintained by the X12 External Code Lists; always verify against the current X12 release and the payer's own published policy before submitting or appealing a claim.