CO 207 denial code

Claim adjustment reason code 207. Often reported as CO 207.

NPI in an invalid format

Unofficial reference. This is our own plain-English explanation, not the official code text. Payer rules differ. Verify with the payer and the official X12 code list. AlphaPrefix is not affiliated with X12, CMS or any payer. Data last updated Nov 11, 2026.

What 207 means

An NPI on the claim does not have a valid structure, such as the wrong length or a failed check digit.

NPIs are ten digits with a built-in check digit. The payer looked at an NPI on this claim and found it could not be a real one.

Typos, transposed digits, or a different identifier typed into the NPI field are the usual reasons. Correct it and resubmit.

Group codes seen with 207

On a remittance, 207 comes after a group code. These are the ones it is most often reported with:

• CO 207 (Contractual Obligation): The provider's side of the ledger. The reduction comes from the payer contract or a rule the provider has to follow, and the patient normally cannot be billed for it.

The payer chooses the group code for each adjustment, so the same reason code can appear with another group code on your remittance. Read the two together. More about group codes.

Common causes

• Two digits were transposed when the NPI was keyed in.
• A tax ID, license number or legacy payer ID was entered in the NPI field.
• The NPI was truncated or padded with extra characters by the billing system.

What to do next

1. Look up the provider's NPI in the national NPI registry and compare it with the claim.
2. Fix the NPI in the provider master file, not just on this claim.
3. Resubmit the corrected claim and watch for the same error on other claims for that provider.

Related codes

• 206 (reason code) NPI missing
• 208 (reason code) NPI does not match payer records
• 16 (reason code) Missing information or billing error