CLIA Proficiency Testing Requirements
CLIA requires labs doing nonwaived testing to enroll in a CMS-approved proficiency testing (PT) program for each regulated analyte. Labs must test PT samples like patient specimens, with no referral or communication between labs. Most analytes need a score of at least 80 percent. Failing the same analyte in two consecutive or two of three events is unsuccessful.
Key facts and official sources
Enrollment and testing rules: 42 CFR 493.801. Full rules: Subpart H.
Successful participation: §493.803
Analytes that are not regulated still need accuracy verified at least twice a year (§493.1236).
How PT works
Programs send samples several times a year, usually in three events.
Test the samples the same way as patient specimens, in the normal workload, by the personnel who routinely test.
Never send PT samples to another lab, and never discuss results with other labs before the deadline.
The director and analyst sign attestations. Keep records at least two years.
Scoring
Satisfactory: at least 80 percent for most analytes. ABO grouping, D typing and compatibility testing require 100 percent.
Unsatisfactory: a failed event.
Unsuccessful: failing the same analyte, test or specialty in two consecutive events or in two of three events. This can lead to sanctions. See unsuccessful PT.
PT checklist
Enroll for every regulated analyte on the menu
Use a PT calendar and assign testers
Handle samples like patient specimens
Sign attestations
Review every graded result, including passes with bias
Investigate failures with documented root cause and corrective action
Keep records at least 2 years
How SLC helps
SLC sets up and reviews proficiency testing programs and investigates PT failures. It does this as part of quality management for CLIA labs nationwide. Related: QMS, PT changes.
FAQs
Do waived labs need PT? No. CLIA PT applies to nonwaived testing.
What if no PT program covers my test? Verify its accuracy at least twice a year by another method, such as split samples.
Can we rerun a PT sample? Only if you would rerun a patient specimen under the same conditions.
What happens after one failure? Document the investigation and corrective action. A second failure in the window makes the result unsuccessful.
Who can test PT samples? The personnel who routinely test patient specimens, using the lab's normal methods.
Does referring PT samples to another lab matter? Yes. It is prohibited and can lead to revocation of the CLIA certificate.
Work with Sound Lab Consultants
Sound Lab Consultants (SLC) is a clinical laboratory consulting company. It provides CLIA compliance, lab startup and licensing, quality management, laboratory director and consultant personnel, and deficiency resolution services to labs nationwide. SLC works with labs accredited by CAP, COLA and The Joint Commission and prepares them for those inspections. Mailing address: PO Box 2135, Chandler, AZ 85244.
Last reviewed Oct 2026 · Sound Lab Consultants CLIA team · General information, not legal advice.