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N300 Remark Code: Occurrence Span Date Invalid

N300 means an occurrence span date on the claim was missing, incomplete, or invalid. Occurrence span codes describe events that last over a period, and each needs a valid 'from' and 'through' date that the payer could not accept as reported.

Quick facts

Code
N300 (RARC N300)
Status
Active In use since December 2, 2004.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The facility must correct the span dates; the adjustment is not patient responsibility.
Official description
Missing/incomplete/invalid occurrence span date(s).
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N300 means

Where an occurrence code marks a single event on a date, an occurrence span code marks a stretch of time. Skilled nursing claims, for example, often use a span to show the dates of the qualifying hospital stay. Other spans describe leaves of absence or periods of non-covered care. N300 says the payer found a problem with the dates attached to one of those spans.

The payer typically pairs it with CARC 16 because it can’t correctly evaluate coverage without an accurate span.

Typical date problems

ProblemExample
One side missingA ‘from’ date with no ‘through’ date
Reversed range‘Through’ date earlier than ‘from’ date
Conflicts with the claimA leave-of-absence span that falls outside the statement period
Wrong stayA qualifying stay span that doesn’t match the hospital’s actual admission and discharge
Format errorDates in the wrong format or with impossible values

How to fix it

  1. Identify the span code on the claim and what event it describes.
  2. Pull source records, such as the prior hospital discharge summary or the facility’s leave log, to confirm the real dates.
  3. Correct both dates and make sure they fall logically relative to the claim’s statement period.
  4. Remove span codes that don’t apply.
  5. Rebill as a replacement claim with frequency code 7.

How to prevent it

Span dates are often keyed from outside documents, which makes typos common. Validate every span for completeness and logical order before release. For qualifying-stay spans, attach the prior hospital’s admission and discharge dates to the patient’s record at admission so billing doesn’t have to chase them later. The CARC and RARC guide shows how to track remarks like N300 to catch recurring registration issues.

Codes that may appear with N300

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): Missing or invalid information; N300 names an occurrence span date.
  • M46 (Missing/incomplete/invalid occurrence span code(s).): The occurrence span code itself is missing or invalid.
  • N299 (Missing/incomplete/invalid occurrence date(s).): A single occurrence date, rather than a span, is the problem.
  • N832 (Duplicate occurrence code/occurrence span code.): A duplicate occurrence or occurrence span code was reported.

N300 FAQ

Where are occurrence span codes reported?

UB-04 form locators 35 and 36, each with a code, a 'from' date, and a 'through' date. The 837I carries the same information.

What kinds of events use a span?

Events with a duration, such as a qualifying prior hospital stay for skilled nursing coverage, a period of non-covered care, or a leave of absence.

Can the 'through' date be the same as the 'from' date?

For a one-day span that may be acceptable, but the 'through' date must never be earlier than the 'from' date.