PR 177 denial code

Claim adjustment reason code 177. Often reported as PR 177 or CO 177.

Eligibility requirements not met

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 177 means

The payer decided the patient did not meet the plan's eligibility requirements for this service.

The patient may have coverage, but did not meet a condition for this benefit, such as age, status or program criteria. This is different from having no coverage at all.

Check the patient's eligibility for the specific benefit, not just active coverage, and confirm the details on file are correct.

Group codes seen with 177

On a remittance, 177 comes after a group code. These are the ones it is most often reported with:

• PR 177 (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.
• CO 177 (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.

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

• The patient did not meet age, status or program criteria for the benefit.
• Details on file with the payer, such as dependent status, were out of date.
• The service is limited to members enrolled in a specific program.

What to do next

1. Run an eligibility check for this specific benefit and date of service.
2. Ask the patient to update their details with the plan if they are wrong.
3. Check for other coverage that could pay for the service.

Related codes

• 27 (reason code) Service after coverage ended
• 178 (reason code) Spend down not met
• 179 (reason code) Waiting period not met