CO-8: procedure code inconsistent with provider type.

What X12 says CARC 8 means

The procedure code is inconsistent with the provider type/specialty (taxonomy).

CARC 8 · Start 01/01/1995, last modified 07/01/2017.

X12 usage note: Refer to the 835 Healthcare Policy Identification Segment (loop 2110 Service Payment Information REF), if present.

In plain terms: The procedure code does not fit the provider type or specialty on the claim.

What it means on a remittance

The payer matched the billed procedure code against the provider type or taxonomy it holds for the provider and found that the combination is not allowed. The X12 usage note points to the 835 Healthcare Policy Identification Segment, which can name the policy behind the edit. A related code, CARC 172, has X12 text about payment being adjusted for a provider of a given specialty.

Typical causes

• The claim carries a taxonomy code that does not match the provider’s enrollment.
• The service was billed under the wrong rendering provider, for example a supervising physician or a different clinician.
• The payer’s file lists an older or incomplete specialty for the provider.
• The payer limits the code to certain provider types and this provider is not on that list.

These are common billing patterns, not a diagnosis of your claim. The remittance and the payer's policy decide.

What to check

1. Compare the taxonomy and NPI on the claim with the provider’s enrollment record.
2. Confirm who rendered the service and who is billing.
3. Check the payer’s policy for provider types allowed to bill the code.
4. Read the REF segment of the 835, if present.

Correct, resubmit or appeal

If the claim named the wrong provider or taxonomy, correct it and resubmit. If the payer’s file is out of date, ask for an enrollment update and reprocessing. If the provider type truly is not allowed to bill the code, follow your contract and the payer’s appeal process.

Medicare dates that apply

A Medicare redetermination request must be filed within 120 calendar days from the date a party receives the notice of the initial determination; receipt is presumed 5 calendar days after the notice date unless there is evidence to the contrary (42 CFR 405.942(a)), and a late request can be considered for good cause (405.942(b)). Other payers set their own appeal windows in the contract or plan documents, so read the notice for the date. The tool above runs the date math.

Related codes

X12 does not publish a table that pairs each code with remark codes; the payer picks the remark code and prints it beside the CARC on the same remittance line.

Other codes: CARC 172 (payment adjusted by specialty), CARC 4 (modifier does not fit the procedure) and the full lookup.

Worked example (hypothetical)

A nurse practitioner’s visit denies with CO-8. The claim listed the supervising physician’s taxonomy on the rendering line. The biller corrects the rendering provider and resubmits.

Sources

• X12: Claim Adjustment Reason Codes — code text, usage notes and dates (list dated 10/30/2026, retrieved 2026-11-02)
• 42 CFR 405.942 — eCFR, current through 2026-10-29 (retrieved 2026-11-02)

Code descriptions are X12 copyrighted material, quoted here only for the codes on this page and linked to the owner. For the full lists, use X12. The X12 text and the Medicare rule above were read from these pages on November 2, 2026. Causes, checks and examples are general billing practice written for this page, not X12 content. Payers revise code lists, contracts and policies, so confirm anything that affects a claim or a deadline with the payer.