CO 184 denial code

Claim adjustment reason code 184. Often reported as CO 184.

Ordering provider not eligible

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 184 means

The payer will not pay because the provider listed as prescribing or ordering was not eligible to order this service.

The payer does not accept the prescribing or ordering provider for this service. Often the provider is not enrolled, or is not a type allowed to order it.

This is common on lab, imaging, equipment and supply claims. Check the ordering provider's details on the claim and the payer's enrollment status.

Group codes seen with 184

On a remittance, 184 comes after a group code. These are the ones it is most often reported with:

• CO 184 (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

• The ordering provider is not enrolled with the payer.
• The ordering provider's type cannot order this service or item.
• The ordering provider's name or NPI on the claim was wrong.

What to do next

1. Check the ordering provider's name and NPI on the claim.
2. Confirm with the payer that the ordering provider is enrolled and eligible.
3. Correct and resubmit, or get a new order from an eligible provider.

Related codes

• 183 (reason code) Referring provider not eligible to refer
• 173 (reason code) Not prescribed by a physician
• 185 (reason code) Rendering provider not eligible