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N320 Remark Code: Home Health Certification Period

N320 means the home health certification period was missing, incomplete, or invalid. Home health services are furnished under a physician- or practitioner-certified plan of care for a defined period, and the payer couldn't accept the period reported.

Quick facts

Code
N320 (RARC N320)
Status
Active In use since December 2, 2004.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The home health agency must correct the certification data; the patient is not billed for this adjustment.
Official description
Missing/incomplete/invalid Home Health Certification Period.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N320 means

Home health care is provided under a plan of care that a physician or allowed practitioner certifies for a specific period. Payers use the certification period to confirm that the visits billed were covered by a valid certification. N320 tells you the certification period on the claim was missing, malformed, or didn’t fit the claim’s dates.

It typically comes with CARC 16.

Common causes

  • The certification period’s start or end date wasn’t reported.
  • The billing period falls partly outside the certification period.
  • A recertification was completed, but the claim still carries the prior period.
  • The period reported doesn’t match the signed plan of care on file.
  • Dates were keyed with typos, or the end date is before the start date.

How to fix it

  1. Pull the signed plan of care and any recertifications for the patient.
  2. Confirm the period that covers the billed visits, including the exact start and end dates.
  3. If visits fall after the certification ended and no recertification exists, resolve that before resubmitting.
  4. Correct the certification period on the claim so it matches the signed documentation.
  5. Resubmit according to the payer’s rules for home health corrections.

How to prevent it

Keep certification periods as structured data tied to the plan of care, and have claims read the period from there. A dashboard of upcoming recertification deadlines helps clinical staff obtain signatures before a period lapses. Before claims drop, compare the billing period with the active certification period and hold any claim that falls outside it. For documentation-driven denials in general, our CARC 16 guide has more detail.

Codes that may appear with N320

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): Missing or invalid information; N320 names the home health certification period.
  • N238 (Incomplete/invalid physician certified plan of care.): The physician-certified plan of care is incomplete or invalid.
  • M141 (Missing physician certified plan of care.): The physician-certified plan of care is missing.
  • N322 (Missing/incomplete/invalid last certification date.): The last certification date is missing or invalid.
  • N309 (Missing/incomplete/invalid assessment date.): The assessment date is missing or invalid.

N320 FAQ

What is a home health certification period?

The span of time a certifying physician or allowed practitioner has certified the patient as eligible for home health under a plan of care.

Is the certification period the same as the billing period?

Not necessarily. Under Medicare, for example, payment periods are shorter than the certification period. Other payers set their own structures.

What if the certification expired before the visit?

Services after the certification ends need a recertification. Correcting dates on the claim won't cure a lapsed certification.