> ## Documentation Index
> Fetch the complete documentation index at: https://dso.getlemma.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Group codes (CO, PR, OA, PI)

> How the four X12 claim adjustment group codes allocate amounts among the payer, provider, and patient, with posting and billing guidance.

**Group codes** appear in the `CAS` segment of the 835 immediately before the CARC. They indicate how the payer classified an adjustment and who may be responsible for the amount.

## The four codes

| Code   | Name                           | Means                                                      | Your action                                         |
| ------ | ------------------------------ | ---------------------------------------------------------- | --------------------------------------------------- |
| **CO** | **Contractual Obligation**     | The provider absorbs it under the contract                 | **Write it off.** You may **not** bill the patient. |
| **PR** | **Patient Responsibility**     | The patient owes it                                        | **Bill the patient.**                               |
| **OA** | **Other Adjustment**           | Neither of the above, usually informational, or a transfer | Depends; often a transfer to a secondary payer      |
| **PI** | **Payer Initiated Reductions** | The payer's own decision, not contractual                  | Often **appealable**                                |

## Why the group code matters

Group-code mapping determines how adjustments reach the patient ledger.

* **Posting a PR amount as CO** can prevent a valid patient balance from entering the statement cycle.
* **Posting a CO amount as PR** can cause the practice to bill an amount that its payer contract requires it to absorb. That may create a contract, compliance, and patient-service problem.

Test your auto-posting configuration against a real 835 before going live, and re-test after any system change. See [Post payments from 835s](/guides/billing/post-payments-from-835s).

## CO, contractual obligation

The most common group code. The provider absorbs the amount because the participation agreement says so.

| Common pairing | Meaning                                                                           |
| -------------- | --------------------------------------------------------------------------------- |
| **CO-45**      | Charge exceeds the fee schedule; commonly posted as the contractual write-off     |
| **CO-197**     | Required authorization was absent; review the contract before billing the patient |
| CO-29          | Timely filing expired                                                             |
| CO-97          | Bundled into another service                                                      |
| CO-253         | Medicare sequestration; rare in dental                                            |
| CO-18          | Duplicate claim                                                                   |

When CO-197 reports a missing authorization as a contractual obligation, the practice will generally need to absorb the amount unless the contract and applicable patient-notice rules permit another result. Confirm the authorization history and the plan terms before moving any balance to the patient.

## PR, patient responsibility

The payer reports the amount as patient responsibility. Confirm any contract or notice requirements before moving it to the patient ledger and statement cycle.

| Common pairing | Meaning                                                 |
| -------------- | ------------------------------------------------------- |
| **PR-1**       | Deductible                                              |
| **PR-2**       | Coinsurance                                             |
| **PR-3**       | Copay                                                   |
| PR-96          | Non-covered charge, where the patient is responsible    |
| PR-204         | Not covered under the benefit plan                      |
| PR-227         | Information requested from the patient was not provided |

<Tip>
  For **PR-96** and **PR-204**, whether you can actually collect depends on your contract and on whether the patient received proper advance notice. Confirm before billing.
</Tip>

### Downgrades: watch where the difference lands

When a plan prices a service at an alternate benefit, such as a posterior composite at an amalgam allowable, the remittance allocates the difference through the same group codes used for other adjustments. Plans and participation agreements differ on how much becomes patient responsibility. Read the actual remittance and the plan's alternate-benefit clause before billing the patient, and include known downgrade behavior in treatment-plan estimates. See [Denials vs downgrades](/concepts/payments/denials-vs-downgrades).

## OA, other adjustment

Used where neither CO nor PR applies. Frequently informational, or a transfer.

| Common pairing | Meaning                                                             |
| -------------- | ------------------------------------------------------------------- |
| **OA-23**      | The impact of prior payer adjudication, appears on secondary claims |
| OA-22          | May be covered by another payer                                     |
| OA-100         | Payment made to the patient, you recover from them                  |
| OA-94          | Processed in excess of charges                                      |

## PI, payer initiated reductions

The payer reduced payment based on its own determination rather than identifying the amount as a contractual obligation. Review the CARC, RARC, plan policy, and contract to determine whether an appeal is available.

PI adjustments are less common than CO and PR adjustments and should generally enter a review queue rather than being written off automatically.

## Quick reference: can I bill the patient?

| Group code | Bill the patient?                                                                                                                  |
| ---------- | ---------------------------------------------------------------------------------------------------------------------------------- |
| **CO**     | Generally no; treat it as the provider's obligation unless the payer corrects the classification or another permitted rule applies |
| **PR**     | Potentially, after confirming the remittance, contract, and any notice requirements                                                |
| **OA**     | Depends, read the CARC                                                                                                             |
| **PI**     | Usually no; consider appealing instead                                                                                             |

## Configuration checklist

For your auto-posting setup:

* [ ] **CO** → contractual adjustment write-off account
* [ ] **PR** → patient ledger, into the statement cycle
* [ ] **OA-23** on a secondary claim → informational, not an adjustment
* [ ] **OA-100** → patient recovery workflow
* [ ] **PI** → review queue, not auto-write-off
* [ ] **Any group code with a \$0 payment and a denial CARC** → denial queue, **not** write-off
* [ ] **PLB segments** → handled separately from claim-level adjustments

<Warning>
  Do not automatically write off a \$0-paid line with a denial CARC. Route it to the denial queue with a root-cause tag so staff can determine whether it should be corrected, appealed, transferred to the patient, or written off. See [Work the denial queue](/guides/billing/work-the-denial-queue).
</Warning>

## A note on RARC MA13

If **MA13** appears on a remittance, review the group-code mapping before billing the patient. The remark warns against billing amounts that were not reported with a patient-responsibility group code.