CARC 303 Active

OA-303: Prior Payer Patient Responsibility Not Covered for QMB

TL;DR

Accept the COB adjustment. The QMB balance-billing prohibition is federal law and this adjustment is not appealable.

Action
Review & Decide
Who Pays
Depends
Appeal
No
Patient Impact
Indirect
Disclaimer
This content is for informational purposes only and does not constitute professional billing advice. Always verify information against your payer contracts and current coding guidelines. Consult a certified billing specialist for specific claim issues.

What Does OA-303 Mean?

The OA group code reflects the coordination between Medicare and Medicaid for QMB patients. Neither the provider nor the patient is responsible for the cost-sharing amount — it is an adjustment resulting from the federal QMB balance-billing prohibition.

CARC 303 applies to Qualified Medicare Beneficiaries (QMB) — dual-eligible individuals who have both Medicare and Medicaid coverage. Under federal law, providers are prohibited from billing QMB patients for Medicare cost-sharing amounts such as deductibles, coinsurance, and copayments. When Medicaid (or the state program) does not cover these cost-sharing amounts, the provider must absorb them.

This code appears when the provider attempted to collect or bill the patient's Medicare cost-sharing, or when the coordination between Medicare and Medicaid results in the cost-sharing amount being written off. The provider cannot balance-bill the patient for this amount regardless of whether the state Medicaid program pays the cost-sharing.

Common Causes

Cause Frequency
COB adjustment for QMB patient Medicare-Medicaid coordination results in the patient responsibility being written off as neither payer covers it Most Common
State Medicaid policy limitation State Medicaid does not pay Medicare cost-sharing amounts for certain services, resulting in an OA adjustment Common

How to Resolve

  1. Accept the OA adjustment as the cost-sharing absorption for QMB patients
  2. Verify the patient's dual-eligible status
  3. If you believe the adjustment is incorrect, contact both Medicare and Medicaid for clarification
Do Not Appeal This Code

CARC 303 with OA reflects the federal QMB balance-billing prohibition. The cost-sharing amount must be written off and cannot be collected from the patient or appealed.

Common RARC Pairings

The RARC code tells you exactly what triggered the OA-303:

RARC Description
N130 Alert: You may need to review plan documents or guidelines. Review Medicaid plan documents for QMB cost-sharing policies →

How to Prevent OA-303

Also Filed As

The same CARC 303 may appear with different Group Codes:

CO-303 PR-303

Related Denial Codes

OA-144 — Incentive Adjustment for Preferred Product/Service OA-195 — Refund to Erroneous Priority Payer OA-198 — Precertification/Authorization Limits Exceeded OA-A0 — Patient Refund Amount OA-B9 — Patient Enrolled in Hospice

Sources

  1. https://x12.org/codes/claim-adjustment-reason-codes
  2. https://www.mdclarity.com/denial-code/303
  3. https://www.cms.gov/medicare-medicaid-coordination/medicare-and-medicaid-coordination/medicare-medicaid-coordination-office
  4. Codes maintained by X12. Visit x12.org for official definitions.