835 Denial Combination

CO-16+MA04

CO

Contractual Obligation · Claim + Service Level Adjustment

Missing Information

What This Combination Means

This combination appears on secondary claims where the payer cannot process payment because primary payer information is missing, incomplete, or illegible. The claim contains a billing error related to coordination of benefits data that prevents secondary adjudication. The provider must write off the adjustment under contractual terms until corrected information is submitted.

Financial Responsibility

provider writeoff

Provider must write off this amount under contractual obligation terms. The patient cannot be billed for the adjustment until the claim is corrected and reprocessed with complete primary payer information.

N/A

Appeal Success

Corrected claim submission (30-45 days typical cycle)

Avg. Resolution

Medium

Difficulty

No

Appealable

Step-by-Step Resolution

Steps tailored specifically to this CO-16+MA04 combination — not generic advice.

Not Appealable:This is a correctable billing error under contractual terms, not a medical necessity or coverage determination subject to appeal.
  1. 1

    Obtain complete primary payer EOB or remittance information

    Secure legible documentation showing primary payer name, payment amount, claim number, and patient responsibility from the primary insurance carrier

  2. 2

    Verify coordination of benefits fields are populated correctly

    Ensure Loop 2330B (Other Subscriber Information) and Loop 2320 (Other Subscriber segment) contain accurate primary payer identification, payment amounts, and patient responsibility

  3. 3

    Submit corrected claim with complete primary payer data

    File as a corrected claim (Claim Frequency Code 7) including legible primary EOB attachment and populated COB fields to allow secondary adjudication

Specialty Context

How CO-16+MA04 typically presents across different practice types.

Dental

Common when dual coverage exists (e.g., patient has both employer dental and spouse's dental plan) and primary carrier EOB was not attached or primary payment information was incomplete in COB fields

Medical

Frequently occurs with Medicare/Medicaid dual eligibles, Medicare Advantage crossover claims, or commercial secondary claims where primary carrier remittance data is missing or illegible on claim submission

Behavioral Health

Appears when behavioral health services are covered under multiple policies (medical and EAP, or parent and student plans) and primary mental health benefit payment information was not included or readable

Individual Code References

View the standalone definition for each code in this combination.

CARC 16RARC MA04

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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