Skip to main content

CO-243 Denial Code: Not Authorized by Network or PCP

CO-243 means the services were not authorized by the patient's network or primary care provider. The plan requires a referral or approval from the PCP or network before specialty or other services, and none was on file for this claim.

Quick facts

Code
CO-243 (CARC 243)
Status
Active In use since June 3, 2012; last modified June 2, 2013.
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): The provider is responsible for not obtaining the required referral. The amount generally cannot be billed to the patient.
  • PR (Patient Responsibility): Sometimes used when the plan holds the member responsible for self-referring. Check plan terms and contracts before billing the patient.
Official description
Services not authorized by network/primary care providers.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-243 means

CARC 243 says the services were not authorized by network/primary care providers. It applies to gatekeeper-style plans, most often HMOs and some Medicaid managed care plans, where the member’s primary care provider must refer the member before a specialist or other service is covered.

The service itself may be in network and medically necessary. The denial is about the missing permission from the PCP or network. X12 split deactivated code 38 into CO-242 (not provided by a network provider) and CO-243 (not authorized by one), so if you see 243, the network status of the rendering provider is not the main issue.

Common causes

  • No referral on file from the patient’s PCP for the specialist visit.
  • Referral expired or used up its approved number of visits.
  • Referral from the wrong PCP, such as a provider who is not the patient’s assigned PCP.
  • Referral not entered in the payer’s system by the PCP office.
  • Referral number or referring NPI missing from the claim (box 17b, box 23).
  • Patient changed plans into a referral-required product without the practice knowing.

How to fix it

  1. Check the payer portal for any referral on file: dates, number of visits, referring provider, and specialty.
  2. If a valid referral exists but was not on the claim, add the referring provider and referral number and submit a corrected claim (frequency code 7).
  3. If no referral exists, contact the PCP office to ask whether a retroactive referral is possible under the plan’s rules.
  4. If a retro referral is issued, resubmit or appeal as the payer instructs, attaching or referencing the referral.
  5. If the referral cannot be obtained, the denial generally stands. Do not bill the patient under the CO group.

Authorization and referral denials covers building referral checks into scheduling.

How to prevent it

  • Check whether the patient’s plan requires referrals at scheduling, not at check-in.
  • Confirm the referral is on file with the payer, covers the date, and has visits remaining.
  • Track referral visit counts and expiration dates, and request renewals early.
  • Put the referring provider’s NPI and the referral number on every claim that needs them.
  • Recheck plan type at each visit, since patients can move to referral-required products at open enrollment.

Specialty notes

Specialists in high-referral fields, such as behavioral health, physical therapy, and dermatology, see CO-243 frequently with HMO members. Multi-visit courses of care often need a referral that covers the full number of visits.

Remark codes that may appear with CO-243

  • N489 (Missing referral form.): The referral form is missing.
  • N335 (Missing/incomplete/invalid referral date.): The referral date is missing, incomplete, or invalid.
  • N630 (Referral not authorized by attending physician.): The referral was not authorized by the attending physician.
  • N286 (Missing/incomplete/invalid referring provider primary identifier.): The referring provider's identifier is missing or invalid.
  • CO-242 (Services not provided by network/primary care providers.): The service was not provided by a network or primary care provider, rather than not authorized by one.
  • CO-197 (Precertification/authorization/notification/pre-treatment absent.): Precertification or authorization from the payer itself was absent.
  • CO-38Deactivated (Services not provided or authorized by designated (network/primary care) providers.): Deactivated predecessor that covered both provided-by and authorized-by network issues.
  • CO-198 (Precertification/notification/authorization/pre-treatment exceeded.): An authorization existed but the services exceeded it.

CO-243 FAQ

What is the difference between CO-243 and CO-197?

CO-243 is about a referral or approval from the network or PCP, typical of HMO plans. CO-197 is about precertification or authorization from the payer. Some services need both.

Can I get a retroactive referral?

Some PCPs and plans allow retroactive referrals within a limited window, and some do not allow them at all. Ask the PCP's office and check the plan's rules, then resubmit or appeal with the referral.

Where do I put the referral on the claim?

Report the referring provider's name and NPI in box 17 and 17b, and the referral or authorization number in box 23 if the payer requires it. Electronic claims carry these in the 837's referring provider and prior authorization fields.