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Claim adjustment reason code

CO-170: Payment denied for this provider type

CO-170 means: Payment is denied when performed/billed by this type of provider. The service may be covered, but not when delivered or billed by a provider of this type.

Read the group code before you act on this

170 is the claim adjustment reason code. The CO in front of it is the group code — a separate field the payer sets on the remittance. The same reason code arrives under different group codes depending on the payer and the situation, and the group code, not the reason code, decides who owes the money.

CO — contractual obligation. You write it off. You may not bill the patient.
PR — patient responsibility. Billable to the patient.
OA — other adjustment, and PI — payer initiated reduction. Neither is patient responsibility.

What causes it

The rendering provider’s taxonomy does not permit this service under the plan
Incident-to billing requirements not met for a mid-level provider
Supervising physician not identified where the payer requires one
A facility service billed on a professional claim or the reverse

How to work it

Confirm the taxonomy code on the claim matches the provider’s actual enrollment, not merely their credential
For mid-level providers, check the payer’s incident-to rules — several require the physician to be on site and to have initiated the plan of care
Where the service should have been billed under the supervising physician, correct and resubmit rather than appealing

How to stop it recurring

This is a credentialing question wearing a billing costume. If a provider type is generating these repeatedly, the enrollment record is what needs fixing.

Who does this work

A credentialing & enrollment seat at $2,200 per seat per month works this queue full time, during your business hours, inside your own system. Every call is logged with the payer reference number and the outcome, and every Friday you get it in writing.

What that seat does →

Check the date behind it, free

Denials in this family are usually a calendar problem wearing a coding costume: a revalidation that lapsed, an enrollment that deactivated, an attestation that expired. CMS publishes every provider’s revalidation due date free.

Look up an NPI → · What deactivation costs

Codes worked the same way

CO-170 is appealed with clinical documentation. So are these, which is why a queue sorted by recovery route moves faster than one sorted by code number — the same person, in the same system, with the same evidence to hand, clears all of them in one pass.

CO-50 — Not deemed medically necessary
CO-151 — Too many services billed
CO-96 — Non-covered charges
CO-234 — Not paid separately
CO-236 — Modifier combination not allowed
CO-231 — Mutually exclusive procedures

Specialties that name this among their costliest

These are specialties whose own worst denials include one of this kind. The line under each is the denial they name, quoted from their page so you can see what the link is based on.

Pain Management
RFA denied because the chart does not carry percent relief and duration from both diagnostic blocks
Orthopedics
Implant and hardware charges denied for missing invoice documentation
Behavioral Health
Time-based psychotherapy codes not supported by documented duration
Cardiology
Stress tests denied for medical necessity documentation
Podiatry
At-risk foot care documentation not naming the treating physician for the systemic condition
Physical Therapy
Timed code units not supported by documented treatment minutes

What leaving it costs

Working a denied claim costs $57.23 per denied claim in administrative time. Source. At 100 denials a month — an illustration, not a measurement of your practice — that is $5,723 a month, or $68,676 a year, in labour alone.

The figure that makes it worth spending: about 90% of initially denied claims are eventually paid. Source. The reason a denial sits is almost never that nobody knows how to work it — it is that nobody has the hours.

Questions

What does denial code CO-170 mean?

Payment is denied when performed/billed by this type of provider. In plain terms: The service may be covered, but not when delivered or billed by a provider of this type.

What causes CO-170?

The rendering provider’s taxonomy does not permit this service under the plan. Incident-to billing requirements not met for a mid-level provider. Supervising physician not identified where the payer requires one. A facility service billed on a professional claim or the reverse.

How do you fix a CO-170 denial?

Confirm the taxonomy code on the claim matches the provider’s actual enrollment, not merely their credential. For mid-level providers, check the payer’s incident-to rules — several require the physician to be on site and to have initiated the plan of care. Where the service should have been billed under the supervising physician, correct and resubmit rather than appealing.

Can CO-170 be prevented?

This is a credentialing question wearing a billing costume. If a provider type is generating these repeatedly, the enrollment record is what needs fixing.

Is CO-170 the same as PR-170?

Same reason, different group code. The number 170 is the reason: The service may be covered, but not when delivered or billed by a provider of this type. The prefix says who carries the amount. CO means contractual obligation — the payer says the amount is not billable to anybody, and it is written off unless the denial itself is overturned. PR-170 is the same reason assigned to patient responsibility — the payer says the amount is owed by the patient, and it is billed to them. Read the prefix before the number: it decides whether you appeal, write off, or bill the patient.

What about the codes next to CO-170?

CO-169 and CO-171 are separate codes and this site does not yet cover them. The authoritative list is the X12 Claim Adjustment Reason Codes at x12.org/codes/claim-adjustment-reason-codes; a code is only described here once its official text, causes and fix have been written and checked.

Code descriptions are the standard X12 claim adjustment reason and remittance advice remark code text. Payer policies differ, and the payer’s own coverage policy governs any individual claim. This page is working guidance, not legal or clinical advice.

Last updated 2026-09-12. This is operational guidance drawn from payer remittance practice, not legal, coding or reimbursement advice. Payer-specific rules vary and change; confirm against the payer’s own policy before acting on a specific claim.

Written by Ibtesam Asif · Last reviewed 2026-09-12

Code descriptions are the standard published text. Everything after them is operational guidance from our own work, and payer policy governs any individual claim.

Other denial codes

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