CARC 133: Claim/Service Pending Further Review

What it means

The payer hasn't made a final decision yet. This isn't a denial — it's a status update telling you the claim is still under review and no payment determination has been issued at this time.

Common causes

• Claim flagged for medical necessity or documentation review
• Claim selected for prepayment audit or clinical validation
• Additional information requested from the provider or another party (e.g., coordination of benefits)
• Claim involves a service requiring manual review (e.g., high-dollar, unusual coding, or new procedure)
• System or workflow backlog on the payer's side

How to fix it

1. Confirm this is a pending status, not a final denial, before taking billing action
2. Check the remittance advice or payer portal for any accompanying remark codes that specify what's needed
3. Contact the payer to ask what triggered the review and what documentation, if any, they need from you
4. Respond promptly to any additional documentation request (ADR) to avoid delays or default denial
5. Track the claim and follow up if no determination is received within the payer's stated review timeframe
6. Avoid resubmitting the claim while it's under review, as this can create duplicate claim issues

Appeal / resubmit

Since this code indicates a pending review rather than a final adverse determination, a formal appeal is typically premature. Wait for the payer's final decision (approval or denial) before filing an appeal. If the review drags on beyond the payer's normal timeframe, follow up in writing and document all communications in case an appeal becomes necessary later.

Frequently asked

More free billing tools: all denial codes · denial lookup · Medicare fee calculator

This content is informational only and does not constitute billing or legal advice. Always verify claim status and requirements with the specific payer.