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N335 Remark Code: Referral Date Missing or Invalid

N335 means the date of the patient's referral was missing, incomplete, or invalid. Payers that require referrals use this date to confirm the referral was issued before the service and was still in effect.

Quick facts

Code
N335 (RARC N335)
Status
Active In use since December 2, 2004.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The claim was denied because the referral date could not be validated. The provider fixes the data; the patient is not billed for this.
Official description
Missing/incomplete/invalid referral date.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N335 means

Plans that require a primary care referral for specialist care check more than the referral number. They also look at when the referral was issued, because referrals often cover a limited window or number of visits. N335 tells you that date was blank, partial, or illogical on the claim.

The remark generally explains CARC 16. If the payer cannot find a referral at all, CARC 288 is more likely; if the visit fell outside the referral’s scope, CARC 287 may appear.

Common causes

  • The referral number was entered but the date field was skipped.
  • The practice reported the date it received the referral rather than the date it was issued.
  • A new referral replaced an expired one, and the old date stayed on the account.
  • The date is later than the service date, often because the referral was obtained after the visit.
  • The claim was built from a template that doesn’t populate referral dates for every payer.

How to fix it

  1. Pull the referral from the payer portal or the referring office and note the issue date, expiration, and visit count.
  2. Confirm the date of service falls inside the referral’s valid period.
  3. Correct the referral date and number on the claim, along with the referring provider name and NPI in box 17 and 17b if needed.
  4. Resubmit as a corrected claim with resubmission code 7 in box 22.
  5. If the referral was issued after the service, ask the payer whether it accepts retroactive referrals before appealing. Our authorization and referral denials guide covers that process.

How to prevent it

Store referrals as structured records with issue date, expiration, and remaining visits, and link them to appointments. Scheduling staff can then see before the visit whether a referral is current, rather than finding out on the remittance.

Codes that may appear with N335

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim is missing information; N335 identifies the referral date.
  • CO-288 (Referral absent): The referral is absent, which may be the real issue if no valid referral existed.
  • CO-287 (Referral exceeded): The referral was exceeded, sometimes discovered once the correct referral date is known.
  • N475 (Missing completed referral form.): Used when the completed referral form itself is missing.
  • N286 (Missing/incomplete/invalid referring provider primary identifier.): Covers a missing or invalid referring provider identifier.
  • N285 (Missing/incomplete/invalid referring provider name.): Addresses a missing or invalid referring provider name.

N335 FAQ

Is the referral date the same as the date of the visit that led to the referral?

Usually it is the date the referral was issued or approved. Payers differ, so use the date shown on the referral record or in the payer's referral portal.

Does fixing the date fix a missing referral?

No. If no referral was obtained, the date correction will not help. You may need a retroactive referral, if the payer allows it, or an appeal.

Where do I find the correct date?

Check the payer's referral portal, the referral letter from the primary care office, or your practice management system's referral record.