Changes to the Clinical Laboratory Improvement Amendments (CLIA)

July 20, 2022

On July 11, 2022, The Centers for Medicare & Medicaid Services (CMS) and the Centers for Disease Control and Prevention (CDC) published the final rule, “Clinical Laboratory Improvement (CLIA) Proficiency Testing Related to Analytes and Acceptable Performance” in the Federal Register.1 The final rule updates proficiency testing (PT) regulations and definitions, and also makes technical changes to PT referral requirements. The final rule is effective in two stages. On August 10, 2022, amendments to 42 CFR 493.20 and 493.25 related to laboratories performing tests of moderate complexity and high complexity that also perform waived testing and proficiency testing are effective. The amendments to 42 CFR 493.2 and 493.801 through 493.959 are effective July 11, 2024.

Participation in PT is required under CLIA for laboratories that perform moderate- or high-complexity testing. PT evaluates a laboratory’s performance by testing unknown samples just as it would test patient samples. A PT program sends samples to a laboratory for analysis. The laboratory reports its results to the PT program; the program then grades the results using the CLIA grading criteria and provides the laboratory with its scores. PT is considered crucial to maintaining the quality of laboratory testing by independently verifying the accuracy and reliability of laboratory testing, including the competency of testing personnel.

Summary of changes2

A PT program must have at least 10 laboratory participants for each specialty, subspecialty, and analyte or test for which the PT program is seeking reapproval.

Two new definitions for “acceptance limit” and “peer group” are included in the final rule, along with a revised definition for “target value.”

Microbiology regulations have been modified to remove the types of services listed for each microbiology subspecialty (bacteriology, mycobacteriology, mycology, parasitology, virology). Instead, broad categories of tests that proficiency testing is required for each microbiology subspecialty have been specified instead.

For non-microbiology specialties and subspecialties (endocrinology, general immunology, routine chemistry, toxicology), 29 analytes were finalized — in addition, criteria for acceptable performance including the target values and acceptance limits have been updated or established by CMS and CDC.

The Department of Health and Human Services may require on-site visits for all initial proficiency testing program applications for CMS approval or when problems are encountered for previously approved proficiency testing programs.


  1. Centers for Medicare & Medicaid Services. Clinical Laboratory Improvement Amendments of 1988 (CLIA) proficiency testing regulations related to analytes and acceptable performance. Federal Register. 2022;87:41194-41242. Accessed July 11, 2022.
  2. Center for Clinical Standards and Quality/Quality, Safety & Oversight Group. QSO-22-21-CLIA. Accessed July 11, 2022.

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