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CO-73 Denial Code (Deactivated): Administrative Days

CO-73 reported administrative days on an institutional claim. X12 deactivated it without naming a replacement, and the official text gives no further detail beyond the phrase itself.

X12 deactivated CARC73 on October 16, 2003. Payers should no longer use it on new remittances, but it can still appear on older ERAs, corrected claims, and appeals.

Quick facts

Code
CO-73 (CARC 73)
Status
Deactivated StoppedOctober 16, 2003 (in use since January 1, 1995).
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): Appeared on hospital remittances to identify days handled differently from acute care days.
Official description
Administrative days.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-73 meant

The official description of CARC 73 is just “Administrative days.” In inpatient billing, administrative days generally refer to days when a patient stays in the hospital for non-clinical reasons, such as waiting for a skilled nursing bed, after acute care is no longer necessary. Some programs reimburse these days at a reduced rate; others do not cover them.

Because X12 gave no definition beyond the two words, how a payer applied it could vary.

What replaced it

X12 did not name a replacement. Payers now describe the financial effect of such days with other active codes:

  • CO-78 for non-covered days or room charge adjustments.
  • CO-186 when payment changes because the level of care changed.
  • CO-50 when the payer finds continued acute days not medically necessary.

If you still see CO-73

Old institutional remittances are the likely source. To reconcile, compare the days reported under CO-73 with the patient’s utilization review record and discharge planning notes. If the payer is applying reduced or no payment to those days today, ask which provision of your contract or the program’s rules governs them, since administrative day rates are often set by contract or state program rules.

  • CO-78 (Non-Covered days/Room charge adjustment.): Non-covered days or room charge adjustment, the closest active inpatient day code.
  • CO-186 (Level of care change adjustment.): Level of care change adjustment.
  • CO-50 (These are non-covered services because this is not deemed a 'medical necessity' by the payer.): Not deemed medically necessary, often used when acute care days are not supported.

CO-73 FAQ

What are administrative days in hospital billing?

The term commonly describes days a patient remains in an acute bed after acute care is no longer needed, often while waiting for placement in a lower level of care. Payers may pay these days at a different rate or not at all.

What code would a payer use now?

It depends on how the payer treats those days. Non-covered days are commonly reported with CARC 78, and level-of-care changes with CARC 186. Ask the payer if the remittance is unclear.