CO 58 denial code

Claim adjustment reason code 58. Often reported as CO 58.

Wrong or invalid place of service

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 58 means

The payer decided the service was performed in a setting where it is not covered or not allowed for this service.

The payer's rules say this service is not appropriate in the setting billed, for example a service that must be done in a facility billed from an office, or the reverse. Unlike a simple mismatch edit, this is about where the service was allowed to happen.

If the place of service code was simply wrong, a corrected claim may fix it. Check the remittance for a service line policy reference, which points to the payer's specific rule.

Group codes seen with 58

On a remittance, 58 comes after a group code. These are the ones it is most often reported with:

• CO 58 (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 place of service code on the claim does not reflect where the patient was actually seen.
• The payer only covers the service in certain settings, such as inpatient or a certified facility.
• A telehealth or home service was billed with a place of service the payer does not accept.

What to do next

1. Confirm the actual location of the service from the encounter record.
2. Send a corrected claim if the place of service code was wrong.
3. Check the payer's policy for the settings where the service is covered.
4. Appeal with documentation if the setting was appropriate and allowed under the policy.

Related codes

• 5 (reason code) Code does not fit the place of service
• 4 (reason code) Procedure code and modifier do not match
• 50 (reason code) Not medically necessary per the payer