Diagnosis invalid for the date of service
The ICD-10 code was not valid on the date of service: it was deleted, replaced, or needs more characters.
CO = Contractual Obligation. The provider owes the difference. The patient cannot be billed for this amount. The same reason code can appear with a different group code; the group decides who may be billed.
Usual causes
- Yearly ICD-10 update (October 1) retired or expanded the code and the system was not updated.
- Truncated code: a code that needs a 5th, 6th or 7th character was billed with fewer.
- Claim coded with a code that did not exist yet.
The fix
Look up the code for the date of service, bill the valid, most specific code and send a corrected claim. Update the code tables in your practice management system every October.
Appeal or corrected claim?
Corrected claim.
Deadline to watch
Timely filing limit.
Exact limits are in your payer contract or provider manual. When in doubt, send the correction or appeal this week.
CO-146 in short
What does CO-146 mean?
The ICD-10 code was not valid on the date of service: it was deleted, replaced, or needs more characters. The official X12 text reads: "Diagnosis was invalid for the date(s) of service reported."
What usually causes a CO-146 denial?
Yearly ICD-10 update (October 1) retired or expanded the code and the system was not updated. Truncated code: a code that needs a 5th, 6th or 7th character was billed with fewer. Claim coded with a code that did not exist yet.
How do I fix CO-146?
Look up the code for the date of service, bill the valid, most specific code and send a corrected claim. Update the code tables in your practice management system every October.
Should I appeal CO-146 or send a corrected claim?
Corrected claim. Corrected claim.
What deadline applies to CO-146?
Timely filing limit.