What does denial code CO-243 mean?

CO-243 means the plan required the services to be authorized or referred by the patient's primary care provider, and no valid referral was on file. It is a gatekeeper requirement rather than a judgment about whether the care was appropriate.

Can a referral be obtained after the visit?

It depends entirely on the plan. Some allow a retroactive referral within a short window after the date of service; others refuse categorically. Ask the payer first, and if it is permitted, have the primary care office submit it with details matching the claim.

CO-243: Services were not authorized by the network or primary care provider

CO-243 is a gatekeeper denial rather than a medical necessity one. Plans built on a primary care referral model require the referral to exist before the specialist visit, and the clinical appropriateness of the care is not in dispute. Whether a referral can be created after the fact is the entire question, and it varies sharply by plan - some allow a short retroactive window, others refuse categorically, which makes checking before the visit far more valuable than working the denial afterwards.

What it means: The plan requires services to be authorized or referred by the patient's primary care provider or network gatekeeper, and no such referral was on file.
Who pays the balance: Contractual in most network agreements - obtaining the referral is generally the provider's administrative responsibility.
Group code CO: Contractual Obligation - the provider absorbs the balance and cannot bill the patient

Why CO-243 happens

The plan requires a primary care referral for specialist visits and none was obtained.
A referral existed but had expired, or covered a different number of visits than were delivered.
The referral named a different specialist or a different service than the one billed.
The patient self-referred without realising the plan required a gatekeeper referral.
The referral was issued but never transmitted to the payer, so it exists on paper and not in their system.

How to fix a CO-243 denial

1
Check whether a referral exists but was not transmitted
A referral issued by the primary care office and never filed with the payer is the easiest version of this denial. Confirm with the referring office before assuming none was created.
2
Ask the payer whether a retroactive referral is permitted
Some plans allow one within a short window after the service; others refuse categorically. This single answer determines whether there is any recovery path at all.
3
Have the primary care provider submit the referral if allowed
The referral has to come from the primary care office, not from the specialist. Provide them with the date of service and the services delivered so it matches the claim.
4
Appeal where the plan's referral rules were misapplied
If the visit was urgent, emergent, or in a category the plan exempts from referral requirements, appeal citing that exemption rather than requesting a referral.

Deadlines depend on the payer

Filing limits and appeal windows for CO-243 vary by payer and often by plan type within the same payer. Look up the specific payer to see its verified deadlines and the source document they came from.

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Preventing CO-243 denials

Verify referral requirements at scheduling for every plan that uses a gatekeeper model, and confirm the referral is on file before the visit.
Track referral expiry dates and visit counts alongside authorizations, since they run out the same way.
Confirm the referral names the correct specialist and service, because a mismatch denies as completely as an absence.

CO-243 frequently asked questions

What does denial code CO-243 mean?: CO-243 means the plan required the services to be authorized or referred by the patient's primary care provider, and no valid referral was on file. It is a gatekeeper requirement rather than a judgment about whether the care was appropriate.
Can a referral be obtained after the visit?: It depends entirely on the plan. Some allow a retroactive referral within a short window after the date of service; others refuse categorically. Ask the payer first, and if it is permitted, have the primary care office submit it with details matching the claim.

Related denial codes

CO-197 PR-242 CO-198 CO-39

Last reviewed August 5, 2026.

Denial code explanations are original plain-English summaries written for reference and are not the official X12 code descriptions. Payer handling of any code varies by contract - always verify against the remittance advice and your payer agreement before adjusting a claim.