How to Appeal CO-233 Denial: Hospital-acquired condition
The service is related to the treatment of a hospital-acquired condition or preventable medical error that CMS does not reimburse. This guide explains what it means, why it happens, and exactly how to build a winning appeal.
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What Does CO-233 Mean?
The service is related to the treatment of a hospital-acquired condition or preventable medical error that CMS does not reimburse.
Commonly seen in:
Step-by-Step Appeal Guide for CO-233
- 1
Request the specific clinical criteria or LCD/NCD the payer used to deny the claim
- 2
Obtain all relevant clinical documentation: progress notes, lab results, imaging, referrals
- 3
Have the treating provider write a letter of medical necessity addressing the denial criteria
- 4
Cite applicable LCDs, NCDs, and peer-reviewed literature supporting the treatment
- 5
Submit the appeal with all documentation and request a peer-to-peer review if available
Counter-Arguments to Use in Your Appeal
These are the strongest arguments medical billing professionals use to overturn CO-233 denials.
Document that the condition was present on admission (POA indicator 'Y')
Provide clinical evidence that the condition was not hospital-acquired
Reference the clinical timeline showing the condition predated admission
Obtain a physician attestation that the condition was present on admission
Regulations and Guidelines to Cite
Citing specific regulations strengthens your appeal and demonstrates you know your rights.
Expert Tip for CO-233 Appeals
The Present on Admission (POA) indicator is critical. If the condition was truly POA, a corrected claim with 'Y' in the POA field should resolve this.
Frequently Asked Questions
What is a CO-233 denial code?
The service is related to the treatment of a hospital-acquired condition or preventable medical error that CMS does not reimburse.
Can I appeal a CO-233 denial?
Yes. All insurance denials are appealable. Follow the step-by-step guide above and submit your appeal before the payer's deadline, typically 180 days from the denial date.
What documentation do I need to appeal CO-233?
For a CO-233 denial, you typically need: the original denial letter/EOB, clinical documentation supporting the service, any prior authorization records, and a cover letter citing the relevant regulations listed above. The specific documents depend on why the denial was issued.
How long does a CO-233 appeal take?
Most payers are required to process standard appeals within 30–60 days. Expedited appeals (for urgent care) must be decided within 72 hours. Under ERISA, group health plans must provide an appeal decision within 60 days for pre-service and 60 days for post-service claims.
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