Denial Code 133 (CO-133, PR-133) — Meaning & What to Do
Claim Adjustment Reason Code (CARC)
What denial code 133 means: The service is still under review (not final).
What to do about denial code 133: Wait for the final decision before paying.
CO-133 vs PR-133 vs OA-133: what the prefix means
| Code on your EOB | What the prefix means | Who typically pays |
|---|---|---|
| CO-133 | Contractual obligation — the provider writes the amount off | Usually not the patient |
| PR-133 | Patient responsibility | The patient |
| OA-133 | Other adjustment | Often another payer or plan |
The prefix tells you who is expected to absorb the amount; the number (133) tells you why.
Seeing denial code 133 on your EOB?
A denial code tells you what the payer reported, but it may not tell the whole story. Reviewing your EOB and bill together can help clarify what may need attention.
Related codes
CARC 132A prearranged demonstration-project adjustment was applied.
CARC 136The claim failed a required 'present on admission' indicator check.
CARC 131A negotiated or contractual discount was applied.
CARC 137A regulatory penalty or fee was applied.
Keep reviewing your bill
- Medical Bill vs EOB: What Is the Difference?
- How to Dispute a Medical Bill — Find Billing Errors Before You Pay
- What Is an Itemized Medical Bill? How to Request One
Frequently asked questions about Denial code 133
What does denial code 133 mean on my EOB?
The service is still under review (not final).
What should I do about denial code 133?
Wait for the final decision before paying.
Seeing this code on your own EOB?
Upload the EOB, the bill, or both — MD Bill Check reads the codes on your documents, compares them side by side, and flags what's worth questioning. Free, no account needed.