CO Y4 denial code

Claim adjustment reason code Y4. Often reported as CO Y4 or PR Y4.

Out-of-network benefits used up

Unofficial reference. This is our own plain-English explanation, not the official code text. Payer rules differ. Verify with the payer and the official X12 code list. AlphaPrefix is not affiliated with X12, CMS or any payer. Data last updated Nov 11, 2026.

What Y4 means

The patient's out-of-network benefits under this plan have run out, so the payer reduced or did not pay this service.

Y4 is a new reason code. It says the plan's out-of-network benefit for this patient has been exhausted, so this out-of-network service was not paid, or not paid in full.

The code does not say whether the limit was a dollar, visit or other cap. Read any remark codes on the line and check the patient's plan terms and the group code before deciding who owes the balance.

Group codes seen with Y4

On a remittance, Y4 comes after a group code. These are the ones it is most often reported with:

• CO Y4 (Contractual Obligation): The provider's side of the ledger. The reduction comes from the payer contract or a rule the provider has to follow, and the patient normally cannot be billed for it.
• PR Y4 (Patient Responsibility): The amount is assigned to the patient. Deductibles, coinsurance and copays are the everyday examples. Whether you can collect it still depends on your contract and the patient's plan.

The payer chooses the group code for each adjustment, so the same reason code can appear with another group code on your remittance. Read the two together. More about group codes.

Common causes

• Earlier out-of-network care used up the plan's out-of-network benefit for the patient.
• Claims from other out-of-network providers counted toward the same limit.
• The provider was out of network for this plan, so the service drew on the out-of-network benefit.

What to do next

1. Confirm with the payer that the provider was out of network for the patient's plan on that date.
2. Ask the payer how much of the out-of-network benefit was used and by which claims.
3. Check whether an in-network exception, referral or network gap rule applies to the service.
4. Check the group code and any agreement with the patient before moving a balance to the patient.

Related codes

• 119 (reason code) Benefit maximum reached
• 242 (reason code) Not provided by a network or PCP provider
• 279 (reason code) Out of the member's preferred network