What is denial code CO-16?
CO-16 means the claim lacks information or has a billing error. A remark code always says what's missing, and the fix is usually a corrected claim.
Remittance advice, claim lines
| Service | Billed | Paid | Adjustment | Remark |
|---|---|---|---|---|
| 97161 PT evaluation | $190.00 | $0.00 | CO-16 $190.00 | N290 |
| J1100 Dexamethasone injection | $24.00 | $0.00 | CO-16 $24.00 | M119 |
- N290: the rendering provider's identifier is missing or invalid. Add the therapist's NPI.
- M119: the NDC for the drug is missing or invalid. Add the 11-digit NDC and units from the vial used.
Reason code 16 reads: Claim/service lacks information or has submission/billing error(s). On its own it says almost nothing, so payers must add at least one remark code explaining what’s wrong.
Common remark codes with CO-16
- M51: missing or invalid procedure code.
- M119: missing or invalid NDC for a drug.
- N290: missing or invalid rendering provider identifier.
- MA130: Medicare’s “unprocessable claim,” which needs a new claim, not a correction.
- N286 and other N-codes: missing or invalid provider, patient or referral details.
How to fix and prevent it
Find the field named in the remark code, fill it from the record, and send a corrected claim or a new one as the payer requires. Most CO-16s are preventable: claim scrubbing catches missing NPIs, NDCs, referral numbers and dates before the claim leaves.
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