N265N-series (general use)Provider Identifiers
N265: Ordering provider identifier missing/invalid
The ordering provider's NPI is missing, invalid, or not enrolled — labs, imaging, and DME claims fail on this constantly (PECOS enrollment for Medicare).
Commonly appears with these denial codes
CO-16CO-183
The denial code gives the category; N265 pinpoints the specific problem. Read them together before touching the claim.
What to do about it
Verify the ordering provider's NPI and Medicare enrollment (PECOS), correct the claim, and resubmit. Validate ordering NPIs at order entry, not at billing.
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