CO · Contractual ObligationCARC 170

Denial Code CO-170

Q: What does CO-170 mean?

CO-170 is a Contractual Obligation (CO) denial: "Payment is denied when performed/billed by this type of provider." The payer won't pay this service when it's performed or billed by this provider type — the service is outside what that provider type/specialty is recognized to perform or bill under the plan.

Q: Is CO-170 the patient's responsibility or a provider write-off?

CO-170 carries the CO group code (Contractual Obligation): Provider/contractual responsibility — not billable to the patient while denied. A CO adjustment is the provider's responsibility, not the patient's: balance-billing the patient for a CO amount is a contract (and often compliance) violation. But CO does not automatically mean “write it off.” When the cause is fixable — missing information (CO-16), a modifier problem (CO-4), or NCCI bundling (CO-97) — you correct and resubmit, or appeal with documentation. You only truly write the amount off when it is a final contractual adjustment, such as the fee-schedule difference on CO-45.

Payment is denied when performed/billed by this type of provider.

Source: X12 Claim Adjustment Reason Codes (CARC) & Group Codes. Maintained by the D3rx Clinical Billing Team.

What CO-170 means

The payer won't pay this service when it's performed or billed by this provider type — the service is outside what that provider type/specialty is recognized to perform or bill under the plan.

Why CO-170 happens

The provider type/specialty isn't recognized to perform or bill this service
A scope-of-practice or licensure limitation on the rendering provider type
An incorrect taxonomy code making the provider look ineligible for the service
A service that must be billed by a different provider type or setting

What to do when you get CO-170

1Confirm the rendering provider's type/taxonomy on the claim is correct
2Check the payer's policy on which provider types may perform/bill this service
3If the taxonomy was wrong, correct it and resubmit a corrected claim
4If the provider type is genuinely eligible, appeal with credentialing/scope documentation

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CO group code: who absorbs the charge

Contractual Obligation — Provider/contractual responsibility — not billable to the patient while denied.

A CO adjustment is the provider's responsibility, not the patient's: balance-billing the patient for a CO amount is a contract (and often compliance) violation. But CO does not automatically mean “write it off.” When the cause is fixable — missing information (CO-16), a modifier problem (CO-4), or NCCI bundling (CO-97) — you correct and resubmit, or appeal with documentation. You only truly write the amount off when it is a final contractual adjustment, such as the fee-schedule difference on CO-45.

Appeal, correct, or write off CO-170?

First rule out a data error: a wrong taxonomy code can make an eligible provider look ineligible — correct it and resubmit. If the taxonomy was right and the provider type IS permitted to perform the service, appeal with licensure/credentialing and the payer's own policy supporting eligibility. If the provider type genuinely can't bill the service, route it to the appropriate provider/setting instead.

Timing & deadlines

Appeal within the payer's window (Medicare redetermination 120 days from the remittance; commercial ~180 days). Corrected claims (taxonomy fix) follow timely-filing limits (Medicare 12 months from date of service; commercial ~90-180 days).

Example

A service is billed with a taxonomy that maps to the wrong specialty, so the payer returns CO-170 (denied for this provider type). Correcting the taxonomy to the provider's actual specialty and resubmitting clears it.

Prevent CO-170 going forward

Verify each provider's taxonomy code matches their specialty and the services billed
Check payer rules on which provider types may bill specific services
Keep credentialing and scope-of-practice records current
Route services to the provider type/setting the payer recognizes for them

Code families most affected

Services with provider-type or specialty restrictions
Mid-level/allied-provider billed services
Taxonomy-sensitive procedures

Related codes

Denial codes you'll often see alongside CO-170

CO-16 CO-299

Payer notes

CO-170 turns on the PROVIDER TYPE performing/billing the service, often surfacing from a taxonomy mismatch. Check the taxonomy first — many CO-170s are data errors rather than true scope limitations.

Turn this CO-170 denial into a sent appeal

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Medical billing disclaimer

CARC/RARC definitions are the standardized X12 set; group-code semantics follow the X12 Claim Adjustment Group Code standard. Filing and appeal windows vary by payer — the standard anchors shown (Medicare redetermination 120 days from the remittance; Medicare timely filing 12 months from date of service; most commercial payers ~90-180 days) are general references, not a guarantee for any specific plan. Always confirm the rule in the payer's provider manual before acting. D3rx is not responsible for claim outcomes.