CO-234 at a glance
CO-234 | |
|---|---|
Group code | CO, Contractual Obligation (X12) |
CARC 234 text (X12) | This procedure is not paid separately. At least one Remark Code must be provided (may be comprised of either the NCPDP Reject Reason Code, or Remittance Advice Remark Code that is not an ALERT.) |
In the X12 list since | January 24, 2010, with no later modification |
Remark code | Required. It carries the actual explanation |
What it means for a therapy practice | One line on the claim was bundled into another or excluded by the payer's payment policy |
Who owes the CO-234 amount | The practice, as a contractual write-off |
Usual action | Read the remark, find the payer policy behind it, and appeal only if that policy doesn't fit the visit |
What the CO-234 denial code description means
The first sentence of CARC 234 is the reason: "This procedure is not paid separately." The second sentence isn't aimed at you. It tells the payer it has to add a remark code, either a Remittance Advice Remark Code that isn't an ALERT or, on pharmacy claims, an NCPDP reject reason.
So CO‑234 by itself says very little. It doesn't name the other procedure, and it doesn't say whether the payer bundled the line because of a coding edit or because the plan never pays that code on its own. Look for the remark on the same service line first, then at the claim level. If neither is there, the remittance is incomplete and you're entitled to ask the payer for the reason.
A worked example: a screening line that comes back at zero
A fictional practice sees a new adult client for a 55‑minute psychotherapy session and gives two standardized screeners at the start, a PHQ‑9 and a GAD‑7. It bills 90837 once and 96127 twice. The plan's remittance comes back like this:
Line | Billed | Adjustment | Paid |
|---|---|---|---|
90837 | $190.00 | CO-45 $50.00, PR-3 $30.00 | $110.00 |
96127, first unit | $15.00 | CO-234 $15.00 | $0.00 |
96127, second unit | $15.00 | CO-234 $15.00 | $0.00 |
The remark on both 96127 lines says the plan treats brief screening instruments as part of the visit they're given in. The client owes the $30 copay from the psychotherapy line and nothing else. The $30 under CO‑234 can't move to the client's balance, because CO assigns it to the provider.
Whether 96127 gets paid next to a session depends on the plan. Some pay it, some bundle it. The practice's job is to know which plans do which, and to stop billing a line that a plan has said in writing it won't pay.
CO-234 vs CO-97, CO-231 and CO-236
Four CARCs describe a service that isn't paid because of another service or a payment rule. The X12 wording is what separates them:
CARC | X12 text | What it points to |
|---|---|---|
234 | This procedure is not paid separately. | A bundling or payment-policy decision, explained by the remark |
97 | The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated. | Another service, usually on an earlier claim, that already absorbed this one |
231 | Mutually exclusive procedures cannot be done in the same day/setting. | Two services the payer's edits say can't both happen that day |
236 | This procedure or procedure/modifier combination is not compatible with another procedure or procedure/modifier combination provided on the same day according to the National Correct Coding Initiative or workers compensation state regulations/ fee schedule requirements. | A National Correct Coding Initiative edit, or a workers' compensation fee schedule rule |
CARC 97 has a time element that 234 lacks: the other service "has already been adjudicated". If your session was paid on last week's claim and an add‑on from the same date shows up alone on a new claim, expect 97. If both lines are on one claim and the payer simply won't pay one of them, 234 is the more likely code.
When to appeal a CO-234
- Your contract lists a rate for the code. If the fee schedule attached to your agreement prices 96127 or another add-on, the plan has agreed to pay it. Send the rate page with a reconsideration.
- The remark names a service that wasn't billed. A bundling edit needs two lines. If the other one isn't on the claim, the edit fired in error.
- The two services were at different encounters. A screening done at a separate visit, or a service by a different clinician, may need its own claim or a modifier the payer accepts.
- The payer's policy changed without notice. Ask for the effective date of the policy and the notice it sent to network providers.
If none of those apply, post the write‑off and move on. Repeated appeals of a correct bundling decision cost staff time and get nothing back.
How to work a CO-234 line
- Read the remark code on the line and copy its wording into your denial log with the claim number.
- Look up the plan's reimbursement policy for the code. Large commercial payers usually post them on their provider websites.
- Compare it with your contract. If the contract pays the code, request a reconsideration and attach the rate schedule.
- If the policy applies, post the amount as a contractual adjustment and add a note to the payer's billing profile so the code isn't billed to that plan again.
Session codes these add‑ons usually sit next to: 90837, 90832 and 90791. The add‑on and screening pages are 96127 and 90785.
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Related denial codes: CO-231 for mutually exclusive services, CO-45 for the fee schedule write‑off, CO-18 for an exact duplicate and CO-252 when the payer wants documentation first.
Checked against the X12 Claim Adjustment Reason Code list on October 26, 2026. CARC 234 still has the wording it started with on January 24, 2010, and nothing about it changed this year.