CO-B23 denial code
Procedure billed is not authorized per your CLIA certification
How to fix it
Verify your CLIA certificate covers the test performed. Where it does not, the test is not billable by your practice.
How to prevent it
Match your test menu to your CLIA certificate level, and include the CLIA number on claims requiring it.
In practice
A practice holding a certificate of waiver performs a moderate complexity test in its office laboratory. The claim returns CO-B23, because the test exceeds what the certificate permits.
Laboratory testing is authorised by certificate level, and each level permits a defined range of test complexity. Performing beyond it is not merely unbillable; it is outside the practice's regulatory authorisation.
Verify the certificate level against the test's complexity classification. Where the test exceeds it, the answer is either to upgrade the certificate or to send the test out, not to rebill.
What sits behind it
The certificate levels are distinct and consequential. A certificate of waiver permits only tests classified as waived; a certificate for provider-performed microscopy adds a specific narrow set; certificates for moderate and high complexity require proficiency testing, quality control and personnel standards.
Claims for waived tests generally require the QW modifier alongside the certificate number, and omitting it produces denials on tests the practice is entirely authorised to perform. That is a different problem with the same appearance, and worth ruling out first.
The compliance dimension is larger than the billing one. Performing tests beyond a certificate level is a regulatory matter in its own right, so a denial of this kind is worth treating as a prompt to review the test menu rather than as a claim to fix.
Related codes
Terms used here — Credentialing · Modifier · HCPCS
How we handle it — Provider Credentialing · Medical Coding · Denial Management
Primary sources
The rules behind CO-B23, at the bodies that publish them.
- PECOS Medicare enrollment (opens in a new tab)
Centers for Medicare & Medicaid Services — Where Medicare provider enrollment is filed and maintained. Revalidation deadlines missed here stop payment outright.
- NPI Registry (NPPES) (opens in a new tab)
Centers for Medicare & Medicaid Services — Public lookup and management for National Provider Identifiers. A stale NPPES record is a quietly common cause of enrollment and claim rejections.
- Medicare Claims Processing Manual (opens in a new tab)
Centers for Medicare & Medicaid Services — The operative manual for how Medicare claims must be coded, submitted, adjusted and appealed. When a payer policy and a vendor's advice disagree, this settles it.
Looking for a different code? Search all 190 CARC and RARC codes
Questions about CO-B23
A certificate of waiver permits only waived-complexity tests. Provider-performed microscopy adds a narrow defined set. Moderate and high complexity certificates permit more but require proficiency testing, quality control and specified personnel standards.
It could, and that is worth ruling out first. Waived tests generally require the QW modifier alongside the certificate number, and omitting it produces denials on tests the practice is fully authorised to perform.
No, and that is the more important point. Performing tests beyond a certificate level is a regulatory matter in its own right, so this denial should prompt a review of the test menu against the certificate rather than an attempt to rebill.
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