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N309 Remark Code: Assessment Date Missing

N309 means the assessment date was missing, incomplete, or invalid. Some claims, especially in post-acute settings, depend on the date a patient assessment was completed, and the payer could not accept the date reported.

Quick facts

Code
N309 (RARC N309)
Status
Active In use since December 2, 2004.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): A provider-correctable date problem; the patient is not responsible for the adjustment.
Official description
Missing/incomplete/invalid assessment date.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N309 means

In several care settings, payment and coverage decisions hang on a formal patient assessment. Home health, skilled nursing, and some rehabilitation programs use assessments to set care plans, justify services, and in some cases determine payment. When a payer requires an assessment date on the claim, N309 is how it tells you that date was missing or wrong.

It generally comes with CARC 16, meaning the claim is correctable.

Common causes

  • The claim was generated before the assessment was finalized, leaving the date blank.
  • The date reported was the start-of-care or admission date rather than the assessment date.
  • The assessment date falls outside the billing period in a way the payer’s rules don’t allow.
  • A reassessment was performed, but the claim still carries the earlier date.
  • Dates were entered in the wrong format or with typos.

What to do

  1. Locate the completed assessment in the clinical record and note its completion date.
  2. Confirm which assessment the payer expects for this billing period (initial, follow-up, or reassessment).
  3. Correct the date on the claim and check that it aligns with the related certification or care plan period.
  4. Resubmit with frequency code 7 and the original claim number, or according to the program’s correction rules.

How to prevent it

Link billing to assessment completion. The claim should not drop until the relevant assessment is locked and its date is available to the billing system. Where reassessments are routine, build an edit that compares the assessment date on the claim to the most recent one on file. Clinical and billing teams should share a calendar of assessment due dates so late assessments are flagged before they affect claims.

Codes that may appear with N309

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): Missing or invalid information; N309 names the assessment date.
  • N334 (Missing/incomplete/invalid re-evaluation date.): The re-evaluation date is missing or invalid.
  • N320 (Missing/incomplete/invalid Home Health Certification Period.): The home health certification period is missing or invalid.
  • N313 (Missing/incomplete/invalid certification revision date.): The certification revision date is missing or invalid.

N309 FAQ

Which claims use an assessment date?

Settings where payment or coverage is tied to a formal patient assessment, such as home health, skilled nursing, and some therapy or hospice programs. Requirements depend on the payer and program.

Is the assessment date the same as the visit date?

Not always. It is the date the assessment was completed, which may differ from the dates of service being billed.

What if the assessment was done over several days?

Use the date the payer's rules specify, often the completion date. Check the program's instructions.