Reviewed Sep 20, 2026 · maintained by Erin Rose · general reference, not legal advice
What the remit says
CO-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.”
Verbatim, X12 code lists 11/1/2025.
Why it lands on drug claims
Every NCCI pair has a modifier indicator. Indicator 1 means a distinct-service modifier on the column-2 code opens the edit; indicator 0 means nothing does. The three injection pairs on this page are indicator 1, so the denial is asking a question: was the injection a separate service? The port-flush pair is indicator 0 and no modifier opens it. A different drug by its own order given IM while the infusion ran is exactly that, and XU (unusual non-overlapping service) on the 96372 line answers it.
The same pairs deny differently depending on the payer's remit logic: Medicare contractors and most commercial payers return CO-236 for the NCCI edit; some return CO-97 with M15 for the same event. The fix is the same. What differs is that CO-236 tells you the modifier will work, where CO-97 does not.
Two pairs that are not a modifier question: a port flush (96523) with any infusion or push is included in the administration and never separately reportable on the same day, and hydration concurrent with a drug is incidental. A CO-236 on those lines is correct as filed.
The NCCI pairs behind this denial
| Column 1 (pays) | Column 2 (denies) | Modifier opens it (practitioner) | Edit since | Modifier opens it (facility) |
|---|---|---|---|---|
| 96365 therapeutic IV infusion, initial hour | 96372 SC/IM injection | Yes (indicator 1) | 01/2009 | Yes |
| 96374 IV push, single or initial | 96372 SC/IM injection | Yes (indicator 1) | 01/2009 | Yes |
| 96401 chemo SC/IM injection | 96372 SC/IM injection | Yes (indicator 1) | 01/2009 | Yes |
| 96365 therapeutic IV infusion, initial hour | 96523 port flush | No (indicator 0) | 01/2009 | No |
CMS NCCI procedure-to-procedure edits, practitioner and hospital outpatient tables, Q3 2026. The modifier belongs on the column-2 line.
The fix
- Identify the pair from the two lines and the table above; the column-2 line is the one that denied.
- If the column-2 service was a distinct drug or a separate site/encounter with its own documentation: add XU, XS or XE to the column-2 line and resubmit as a corrected claim.
- If the column-2 service was part of the primary (flush, concurrent hydration, same-drug second push under practitioner rules): remove the line.
- Never put the modifier on the column-1 code; the edit reads the column-2 line.
What to attach
- The MAR showing the second drug, route and time
- The order for the second drug
- For XS/XE: documentation of the separate site or encounter
Corrected claim or appeal?
Corrected claim with the modifier on the column-2 line (XU for a distinct injection, XS/XE for a separate site or encounter) when the second service was real; remove the line when it was part of the primary (flush, concurrent hydration). Not an appeal.
Medicare windows (redetermination 120 days, reconsideration 180 days, ALJ 60 days) and the commercial path are on the denials hub, cited to 42 CFR Part 405 Subpart I; the edits are CMS's NCCI tables.
Frequently asked
- Which line gets XU on 96365 with 96372?
- The 96372, the column-2 code. The 96365 stays as billed. XU is the specific modifier for a distinct injection during an infusion encounter; 59 is accepted where the payer has not adopted the X modifiers.
- Is CO-236 the same as CO-97?
- Same edit, different remit code. CO-236 cites NCCI by name and is returned on pairs with a modifier indicator of 1 or 0; CO-97 is the generic bundling code. When you get CO-236, look up the indicator: 1 means a modifier can reopen it, 0 means it cannot.
- The port flush was a separate order. Can I bill 96523 with the infusion?
- No. NCCI treats the flush as part of any infusion or push on the same day, and the 96523 pair with 96365 is not a modifier question. 96523 pays only when it is the sole service that day.
Related references
See the pair before the payer does
Claim Check flags every NCCI column-1/column-2 pair on the administration lines as you build the visit and tells you which line takes the modifier.
Open Claim CheckSources & how this is maintained
- Computed on this page
- NCCI PTP pair rows for four injection/infusion pairs (modifier indicator, effective date, both tables). Edits vintage Q3 2026.
- Authored
- Why CO-236 is the edit that answers to a modifier, the pairs that never do, and which line carries it.
- Corrections
- Send one with the remit line.