835 Denial Combination

CO-16+N400

CO

Contractual Obligation · Claim-Level Adjustment

Missing Information

What This Combination Means

This combination indicates the claim was submitted with missing information or billing errors while the payer is encouraging electronic submission. The payer is applying a contractual adjustment due to the submission deficiency, suggesting the claim was sent via paper or non-compliant electronic format. The N400 alert signals the payer's preference for proper electronic claim submission to avoid future processing issues.

Financial Responsibility

provider writeoff

The provider must absorb the adjustment amount per contractual agreement with the payer. The patient cannot be billed for this adjustment regardless of the submission method issue.

N/A

Appeal Success

Immediate (write-off)

Avg. Resolution

Easy

Difficulty

No

Appealable

Step-by-Step Resolution

Steps tailored specifically to this CO-16+N400 combination — not generic advice.

Not Appealable:CO adjustments for submission errors are contractual obligations that cannot be appealed; the provider is responsible for proper claim submission format.
  1. 1

    Write off the adjusted amount

    Post the CO adjustment to the patient account as a contractual write-off per payer agreement

  2. 2

    Verify electronic claim submission capability

    Confirm your practice is enrolled for electronic claim submission with this payer to comply with the N400 recommendation

  3. 3

    Identify the missing information or billing error

    Review the original claim against the ERA loop 2110 Service Payment Information REF segment to determine what information was lacking or incorrectly submitted

  4. 4

    Submit a new corrected claim electronically

    File a new claim (not a corrected claim) with complete information using electronic submission to ensure proper processing and avoid future CARC 16 adjustments

Specialty Context

How CO-16+N400 typically presents across different practice types.

Dental

Common when dental practices submit paper ADA 2019 forms instead of using electronic 837D transactions; verify enrollment in payer's electronic dental claim system

Medical

Frequently seen when practices submit paper CMS-1500 forms despite having electronic clearinghouse capability; ensure 837P electronic submission is active for the payer

Behavioral Health

May occur when behavioral health providers use paper claims for privacy concerns; confirm HIPAA-compliant electronic submission is enabled to avoid contractual adjustments

Individual Code References

View the standalone definition for each code in this combination.

CARC 16RARC N400

Medicare Contractor Guidance for CARC 16

FCSO + Noridian + uhc + aetna + bcbs_az

This RUC is received when a claim is submitted with missing, incorrect, or invalid information. For details pertaining to your claim, please refer to the remittance advice remark codes (RARCs) on the remittance advice (RA).

How to Prevent CARC 16 Denials

  • ✓

    Review the RARC on the remittance advice to identify which specific field has the error.

  • ✓

    Per Medicare guidelines, claims must be filed no later than 12 months after the date of service. RUCs are not considered filed/submitted.

CMS guidelines for completion of form CMS-1500 in the Medicare Claims Processing Manual (100-04), Chapter 26SPOTFee Schedule Lookup ToolCMS laboratory demographics lookupModifier lookup toolNoridian Medicare PortalNMPIVRSame or SimilarPECOSPDAC

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Synthesized from official definitions — not from training data

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