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N46 Remark Code: Missing or Invalid Admission Hour

N46 means the admission hour on the claim was missing, incomplete, or invalid. Institutional claims for inpatient and some other facility stays must report the hour the patient was admitted, using the standard hour coding.

Quick facts

Code
N46 (RARC N46)
Status
Active In use since January 1, 2000.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The claim is returned or denied as a correctable facility billing error. It is not a patient balance.
  • PI (Payer Initiated Reduction): Some government payers report it as a payer-initiated adjustment. Correcting the hour resolves it.
Official description
Missing/incomplete/invalid admission hour.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N46 means

Facility claims carry detailed information about when a stay began. The admission hour helps payers compute days, apply rules around observation versus inpatient status, and check overlaps with other claims. N46 says the hour on your claim was blank, not in the expected format, or did not make sense.

It is almost always paired with CARC 16. This is a data-entry issue on institutional claims, not a professional-claim problem.

Common causes

  • The registration system did not pass the admission time to the billing system.
  • The time was entered in a 12-hour format, or with minutes, where the field expects an hour code.
  • The admission hour was left off because the stay converted from observation, and staff were unsure which time to use.
  • The admission date and hour conflict with other dates on the claim, such as service dates before admission.

How to fix it

  1. Confirm the admission time from the admission order or registration record.
  2. Code it correctly. On the UB-04, enter the two-digit hour code in form locator 13. On the 837I, use the admission date-time field in the required format.
  3. Check related fields. Make sure the admission date, type, and source, and the statement dates, all line up.
  4. Resubmit using the payer’s corrected-claim process for institutional claims (typically a replacement type of bill frequency).

How to prevent it

Make the admission time mandatory at registration, and map it automatically to the claim in the right format. Add a claim scrubber edit that flags missing or out-of-range admission hours before submission. Rules on which time to report after an observation stay converts to inpatient vary, so document your facility’s approach based on payer guidance.

Codes that may appear with N46

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim is missing required information; N46 names the admission hour.
  • MA40 (Missing/incomplete/invalid admission date.): The admission date, rather than the hour, is missing or invalid.
  • MA41 (Missing/incomplete/invalid admission type.): The admission type is missing or invalid.
  • MA42 (Missing/incomplete/invalid admission source.): The admission source is missing or invalid.
  • N317 (Missing/incomplete/invalid discharge hour.): The discharge hour is missing or invalid.

N46 FAQ

Where is the admission hour reported?

On the UB-04 it goes in form locator 13, next to the admission date. Electronic institutional claims carry it with the admission date and time.

How is the hour coded?

The UB-04 uses a two-digit hour code from 00 to 23 representing the hour of admission. Electronic claims typically carry the admission time in their own date-time format.

Do outpatient claims need an admission hour?

Generally it is required for inpatient claims and may be required for some other bill types. Payer requirements vary, so check the payer's institutional billing guide.