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CO-D17 Denial Code (Deactivated): Invalid Non-Covered Days

CO-D17 meant an institutional claim reported non-covered days that were invalid. X12 deactivated it and its notes say to use CARC 16 with the appropriate remark code, such as MA33.

X12 deactivated CARCD17 on June 30, 2007. Payers should no longer use it on new remittances, but it can still appear on older ERAs, corrected claims, and appeals.

Code: CO-D17 (CARC D17)
Status: Deactivated StoppedJune 30, 2007 (in use since January 1, 1995).
Code set: Claim Adjustment Reason Codes (CARC)
Group codes: CO (Contractual Obligation): The facility needed to correct its day reporting; the patient was not billed on the basis of this code.
Official description: Claim/Service has invalid non-covered days.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified: September 24, 2026 against the official X12 list.

What CO-D17 meant

Hospitals and other facilities report both covered and non-covered days on inpatient claims. CARC D17 told the facility that the non-covered days it reported did not make sense, such as totals or date spans that did not match the rest of the claim. The payer could not process the claim until they were corrected.

What replaced it

X12’s note says to use code 16 with the appropriate remark code. The current equivalent is CO-16 with remark MA33, which covers missing, incomplete, or invalid non-covered days during the billing period. When the payer accepts that days are non-covered and adjusts payment for them, the code is CO-78.

If you still see CO-D17

It only exists in older institutional files. For a similar rejection today, reconcile the statement period, covered days, non-covered days, and any occurrence span codes on the claim. Correct whichever values are inconsistent and submit a corrected institutional claim.

CO-16 (Claim/service lacks information or has submission/billing error(s).): Named replacement: claim lacks information or has billing errors.
MA33 (Missing/incomplete/invalid non-covered days during the billing period.): Remark code for missing, incomplete, or invalid non-covered days during the billing period.
CO-78 (Non-Covered days/Room charge adjustment.): Non-covered days or room charge adjustment, used when days are validly non-covered.

CO-D17 FAQ

What are non-covered days on an institutional claim?

Days within a stay that the facility reports as not payable, for example days after benefits are exhausted or days not medically necessary. They are reported with value and occurrence span information on the claim.

What makes non-covered days invalid?

Common causes include a day count that does not match the dates reported, occurrence spans outside the statement period, or totals that do not reconcile with covered days and the length of stay.

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