CO-115 denial code
Procedure postponed, cancelled or delayed
How to fix it
Bill the discontinued or reduced service with the appropriate modifier reflecting what was actually performed.
How to prevent it
Establish a process for cancelled procedures so partial services are billed correctly rather than in full or not at all.
In practice
A patient is prepared for an endoscopy and the procedure is abandoned after sedation when a cardiac issue emerges. The practice bills the full procedure code and the claim returns CO-115.
Something happened, and it was not the complete service the code describes. Billing the full code for a procedure that did not proceed misstates what was delivered, and the payer has recognised the discrepancy.
The correct approach is to bill what actually happened using the modifier that describes the stopping point — modifier 53 for a discontinued procedure, 73 or 74 for outpatient hospital cases before or after anaesthesia. Each carries different payment because each describes different resource use.
What sits behind it
The modifier distinctions are precise and the choice affects payment materially. Modifier 53 covers a physician discontinuing a procedure due to risk to the patient. Modifier 73 covers an outpatient facility case terminated before anaesthesia administration, and 74 after it, with the second paying substantially more because the resources were consumed.
Reduced services are a different situation again and use modifier 52, which describes a procedure deliberately performed at less than its full extent rather than one abandoned partway. Confusing the two produces payment that does not match the record.
Documentation is what carries these claims. The note has to establish what was done, at what point it stopped, and why, because the payer is paying for partial work and needs to see where the partial line falls. A note that simply says the procedure was cancelled supports nothing.
Related codes
Terms used here — Modifier · CPT Code · Denial
How we handle it — Medical Coding · Denial Management · Claims Management
Primary sources
The rules behind CO-115, at the bodies that publish them.
- CPT code set (opens in a new tab)
American Medical Association — Maintainer of CPT. Annual changes to CPT are the most common cause of a sudden, unexplained rise in denials each January.
- Claim Adjustment Reason Codes (CARC) (opens in a new tab)
X12 — The authoritative, maintained CARC list. Our denial code lookup explains these in plain English; X12 is where the canonical definitions live.
- National Correct Coding Initiative (NCCI) edits (opens in a new tab)
Centers for Medicare & Medicaid Services — The procedure-to-procedure and medically-unlikely edits behind most bundling denials. Checking these before submission prevents the denial entirely.
Looking for a different code? Search all 190 CARC and RARC codes
Questions about CO-115
Modifier 53 where a physician discontinues due to risk to the patient. In outpatient hospital settings, modifier 73 applies where the case was terminated before anaesthesia and 74 after it, and the two pay very differently because the resources consumed differ.
That distinction decides the modifier. A service deliberately performed at less than its full extent was reduced and takes modifier 52; one started and then abandoned, usually for patient safety, was discontinued and takes modifier 53. They describe different events and pay differently.
A note establishing what was performed, the point at which it stopped, and the clinical reason. The payer is reimbursing partial work and needs to see where the line falls. A note recording only that the procedure was cancelled gives the reviewer nothing to price.
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