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Claim adjustment reason code

CO-242: Services not provided by network providers

CO-242 means: Services not provided by network/primary care providers. The plan pays only for its own network, and this provider was not in it for this service.

Read the group code before you act on this

242 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

Provider not contracted with this plan, as opposed to not contracted with this payer
Contract in place with the payer but not with the specific product the patient holds
Credentialing complete but the effective date after the service
Patient in a narrow-network or exchange product the practice does not participate in

How to work it

Confirm participation for the specific plan and product, not just the payer name. In our experience this distinction accounts for most of these denials.
Check the contract effective date against the date of service.
Where participation exists and the payer’s file is wrong, escalate to provider relations with the contract — and ask for reprocessing of every affected claim, not just this one.
Where the practice genuinely is out of network, check what the patient was told before the visit before any balance moves.

How to stop it recurring

Verify plan-level participation at eligibility. A payer contract does not mean every product under that payer’s name.

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-242 is fixed in credentialing, not on the claim. 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-B7 — Provider not eligible that day
CO-185 — Rendering provider not eligible
CO-8 — Procedure and provider type disagree
CO-107 — Qualifying claim not identified
CO-183 — Referring provider not eligible
CO-184 — Ordering provider not eligible

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.

Pediatrics
Newborn claims denied because the baby was never added to the policy inside the enrollment window
Pulmonology and Critical Care
Sleep study interpretation billed without the qualifying supervision or credentials

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-242 mean?

Services not provided by network/primary care providers. In plain terms: The plan pays only for its own network, and this provider was not in it for this service.

What causes CO-242?

Provider not contracted with this plan, as opposed to not contracted with this payer. Contract in place with the payer but not with the specific product the patient holds. Credentialing complete but the effective date after the service. Patient in a narrow-network or exchange product the practice does not participate in.

How do you fix a CO-242 denial?

Confirm participation for the specific plan and product, not just the payer name. In our experience this distinction accounts for most of these denials.. Check the contract effective date against the date of service.. Where participation exists and the payer’s file is wrong, escalate to provider relations with the contract — and ask for reprocessing of every affected claim, not just this one.. Where the practice genuinely is out of network, check what the patient was told before the visit before any balance moves..

Can CO-242 be prevented?

Verify plan-level participation at eligibility. A payer contract does not mean every product under that payer’s name.

Is CO-242 the same as PR-242?

Same reason, different group code. The number 242 is the reason: The plan pays only for its own network, and this provider was not in it for this service. 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-242 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-242?

CO-241 and CO-243 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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