Proficiency Testing & CLIA Compliance for Clinical Labs

Part-Time vs. Full-Time Laboratory Directors: Making the Right Choice for Your Lab

May 25, 2026

What the 2022 PT Final Rule Changed and How to Pass Every Event Without Risking the Worst CLIA Violation

Few compliance failures can bring clinical laboratory operations to a halt as quickly as a proficiency testing problem.

A laboratory can recover from a documentation gap, a missed temperature log, or a personnel file that needs updating. It rarely recovers from an improper proficiency testing referral, which remains the single violation most likely to cost an owner the CLIA certificate, the right to operate, and in some cases the ability to own or operate any laboratory for a year or more.

Proficiency testing (PT) sits at the center of CLIA compliance because it measures the one thing patients and physicians care about most: whether the laboratory produces accurate results.

The Stakes Couldn’t Be Higher

Despite the consequences of a proficiency testing failure, PT is one of the most misunderstood areas of operation. Many owners treat it as a routine mailing to complete and forget, until a failed event or a surveyor’s question spotlights the problem. The 2022 CLIA PT Final Rule (CMS-3355-F added requirements that took effect on January 1, 2025, and many laboratories are still adjusting.

At Laboratory Management Consultants, we help physician office labs, pain management clinics, startup diagnostic facilities, and established laboratories build proficiency testing programs that pass consistently and steer clear of operation ending violations. This article explains what PT is, what the Final Rule changed, how to enroll correctly, why PT referral is the third rail of CLIA compliance.

What Proficiency Testing Is and Why It Matters

Proficiency testing is an external check on the accuracy of a laboratory’s testing. A CMS-approved PT program sends the laboratory a set of samples with values the laboratory does not know in advance. The laboratory tests those samples exactly as it would test patient specimens, reports its results to the program by a deadline, and receives a graded score comparing its results to the established target values.

The score is not an exercise. Results are reported to CMS and tied directly to the laboratory’s CLIA certificate.

Under CLIA, laboratories performing moderate or high-complexity testing must participate in PT three times per year for each regulated analyte, with testing events spaced across the year (see 42 CFR Part 493, Subpart H). The regulations divide tests into categories that determine the obligation:

Regulated analytes: These appear in Subpart I of the CLIA regulations, and formal PT enrollment is mandatory. Each event is graded, and performance is reported to CMS.
Non-regulated (unregulated) analytes: Formal PT is not required, but the laboratory must verify the accuracy of these tests at least twice per year through an alternative method when no PT program exists.
Waived tests: PT is not required, though the referral rules discussed below now reach waived testing in important ways.

The grading standard is strict. For most quantitative analytes, the laboratory must score acceptably on a set proportion of samples per event (typically at least 80 percent, with many immunohematology and certain other categories requiring 100 percent). Two results drive the consequences:

Unsatisfactory performance: The laboratory failed to attain the minimum satisfactory score for an analyte, test, subspecialty, or specialty in a single event.
Unsuccessful performance: The laboratory failed to attain a satisfactory score for two consecutive events, or for two out of three consecutive events. Unsuccessful performance carries cease-testing consequences.

Because the score flows directly to CMS, a PT program is not a back-office task. It is a recurring, graded demonstration that the laboratory deserves its certificate.

The 2022 PT Final Rule (CMS-3355-F) and What Changed

CMS published the PT Final Rule, CMS-3355-F, on July 11, 2022 (the Federal Register final rule carries the full text). It was the first substantive update to the CLIA proficiency testing regulations since they were established in 1992, modernizing a framework that had not kept pace with three decades of advances in testing. The core provisions of the PT Final Rule (CMS-3355-F) became effective July 11, 2024, with full implementation for laboratories and PT programs on January 1, 2025. As of 2026, laboratories must ensure their programs fully align with the updated requirements.

The changes most likely to affect a working laboratory include:

New regulated analytes: The rule added 29 newly regulated analytes to Subpart I and removed five, expanding the list of tests for which formal PT enrollment is now mandatory. Laboratories that previously verified accuracy for some of these analytes through an alternative method may now need formal enrollment instead.
Revised grading and acceptance limits: CMS and CDC reevaluated target values and acceptance limits across regulated analytes, tightening some and adjusting others. A laboratory that comfortably passed an analyte under the old limits should not assume the same margin under the new ones.
Five-sample programs and combined microbiology: For many newly regulated analytes, laboratories must enroll in five-sample programs, with specific provisions in microbiology where programs may be combined to meet the requirement.
Waived testing and referral clarity: The rule clarified how PT referral provisions apply to laboratories that also perform waived testing. This is an area to confirm directly with your PT provider rather than assume.

The practical takeaway is simple: the analyte list and the grading bar have both changed.

Every laboratory should reconcile its current enrollment against the updated regulated-analyte list and confirm that its PT program reflects the new acceptance limits. The CDC CLIA PT rule resources track the current requirements as they apply.

Enrollment: Matching PT to Your Test Menu

A PT program only protects a laboratory when it matches the test menu precisely. Enrollment errors (signing up for the wrong analyte, missing a subspecialty, or carrying enrollment for a test the laboratory no longer performs) create gaps that surface during inspection. Building enrollment correctly involves several steps:

Select a CMS-approved PT program: Only programs approved by CMS satisfy the requirement. The major accrediting and PT organizations publish current analyte lists and program codes that map to the updated regulations.
Enroll for every regulated analyte and subspecialty on the menu: Cross-walk the laboratory’s full test menu against the regulated-analyte list and enroll for each match, including the correct subspecialty designations. A menu that has grown over time often reveals analytes that were never added to the PT enrollment.
Cover non-regulated analytes with a documented alternative: For tests that have no PT program, the laboratory must assess accuracy at least twice per year using an alternative approach (for example, split-sample comparison with a reference laboratory or a validated alternate method), and must document that assessment.
Retire enrollment that no longer applies: When the laboratory discontinues a test, remove it from the enrollment so the program does not grade an analyte the laboratory does not perform.

This is the kind of detailed, regulation-specific work that benefits from an outside review. An enrollment that looked complete in 2023 may have gaps in 2025 simply because the analyte list changed underneath it. Our Laboratory Setup & Accreditation Guide covers how enrollment fits into the broader compliance picture for new and growing laboratories.

The Cardinal Rule: Never Refer PT Samples

Of every rule in CLIA, one stands apart for the severity of its penalty: a laboratory must never refer its proficiency testing samples to another laboratory for analysis. PT referral is the third rail of laboratory compliance, and it carries consequences that no other deficiency approaches.

Under 42 CFR 493.1840, if CMS determines that a laboratory intentionally referred its PT samples to another laboratory for analysis, the agency imposes sanctions that can include revocation of the CLIA certificate for at least one year, prohibition on the owner/operator from owning or operating any CLIA-certified laboratory for at least one year, and possible civil money penalties in the most serious cases (e.g., repeat referrals or reporting another lab’s results as your own).

CMS interprets ‘intentional’ as the intent to refer the sample, and laboratories are responsible for employee actions. However, legitimate reflex, distributive, or confirmatory testing in full conformance with your written patient-testing SOP is generally not treated as improper referral.

With that in mind, you want to be aware that such referrals can happen by accident. A PT sample that looks like a patient specimen gets caught up in send-out workflow, or a well-meaning technologist sends it out for confirmation the way they would handle a real patient result. The protection is procedural and firm:

Treat PT samples like patient samples in every respect except one: test them in-house exactly as you would a patient specimen, but never let them leave the laboratory. A common safeguard is to flag PT samples in the laboratory information system so they cannot be routed to a send-out queue.
Write a clear PT handling procedure and train every person who touches specimens: the staff most likely to cause an accidental referral are the ones who handle send-outs and reflex testing, so they must understand which samples are PT and why they stay in-house.
Understand the narrow, legitimate exceptions: CMS does not treat a referral as improper when a laboratory shares a specimen for reflex, distributive, or confirmatory testing while acting in full conformance with its written, accurate standard operating procedure for patient testing. The safe path is a written procedure that distinguishes PT samples and stops them before any send-out step.

No single safeguard matters more to certificate protection than a documented, trained, and enforced no-referral procedure for PT samples.

When a PT Event Comes Back Unsuccessful

Even a strong laboratory will occasionally receive an unsatisfactory result. What separates a laboratory that recovers from one that loses testing capability is the response. CLIA expects a structured, documented sequence:

Investigate immediately: Pull the records for the event: the step-by-step handling of the sample, the instrument printouts and raw data, and the result entries. Many failures trace to mundane causes such as a transcription error, a sample mix-up, a barcode on the wrong tube, or a missed step in the package insert.
Perform root-cause analysis: Determine why the result fell outside the acceptable range. Investigate even passing events scored below 100 percent, because a single outlier among five samples can signal a developing problem.
Document corrective action and verify effectiveness: Record the cause, the correction, and evidence that the correction worked. Surveyors look for this documentation specifically.

The stakes escalate with repetition. When a laboratory’s performance becomes unsuccessful (two consecutive events, or two of three consecutive events, for the same analyte, subspecialty, or specialty), CLIA directs the laboratory to cease testing for that analyte, subspecialty, or specialty.

To resume patient testing, the laboratory must demonstrate that it identified and corrected the reason for the unsuccessful performance, then successfully complete two consecutive PT events for the affected test before reinstating it.

A cease-testing directive can also suspend Medicare and Medicaid payment for the affected testing for a period, and CMS publishes an annual registry of sanctioned laboratories.

The CMS Proficiency Testing and PT Referral brochure walks through the reinstatement steps in detail. The corrective-action file a laboratory builds after a single unsatisfactory event is what keeps a second failure, and a cease-testing order, from ever happening.

Building PT Into Routine Operations

A proficiency testing program fails most often not because the laboratory cannot perform the test, but because PT was treated as an exception to normal workflow rather than a part of it. The laboratories that pass consistently build PT into daily operations:

Handle PT samples in the exact manner as patient samples: route them through the same testing process, the same instruments, and the same personnel, with the single difference that they never leave the laboratory. Testing PT samples in a special way defeats the purpose and can itself be a violation.
Calendar the event windows: PT events have firm close dates. A late submission is graded as a zero regardless of the laboratory’s actual accuracy, so the testing windows belong on the operational calendar with reminders well before each deadline.
Capture documentation as you go: retain sample-handling records, instrument output, raw data, and result-entry confirmations for each event, so the file is complete before a surveyor ever asks.
Route every result through the laboratory director: the director should review and sign off on PT results, including passing scores, and lead the investigation when a result is unsatisfactory. This review is both a regulatory expectation and the best early-warning system a laboratory has.

When PT operates inside normal lab procedure, it stops being a source of anxiety and becomes simple proof that the laboratory produces reliable results.

How LMC Helps

Laboratory Management Consultants builds and oversees proficiency testing programs that help your laboratory pass and protect its CLIA certificate. Our PT services span the full lifecycle:

Enrollment guidance: We cross-walk your full test menu against the current regulated-analyte list, confirm you are enrolled with a CMS-approved program for every required analyte and subspecialty, and identify gaps created by the 2022 Final Rule changes.
PT policy and procedure development: We write PT handling and referral-prevention procedures tailored to your specific test menu and workflow, the kind surveyors expect to see and staff can actually follow.
Referral-prevention safeguards: We help you build the LIS flags, send-out controls, and staff training that keep a PT sample from ever leaving the laboratory by accident.
Corrective-action support: When an event comes back unsatisfactory, our consultants guide the investigation, root-cause analysis, and documented corrective action, along with the reinstatement steps if testing must cease.
Ongoing director oversight: Through our Laboratory Director Services, we provide the director-level review and sign-off that CLIA requires, with documented involvement that holds up at inspection.

Our work draws on decades of combined experience across physician office labs, pain management and addiction clinics, startup diagnostic facilities, and established laboratories, along with direct relationships with instrument companies. The result is a proficiency testing program that does what it is supposed to do: keep your certificate secure and your results trustworthy.

Frequently Asked Questions

What is proficiency testing, and is it required for my laboratory?

Proficiency testing is an external check on testing accuracy: a CMS-approved program sends your laboratory unknown samples, you test them like patient specimens, and your graded results are reported to CMS. Under CLIA, laboratories performing moderate or high-complexity testing must participate in PT three times per year for each regulated analyte. Waived-only laboratories are not required to enroll, though the referral rules still matter.

What did the 2022 CLIA PT Final Rule (CMS-3355-F) change?

Published July 11, 2022 with an implementation date of January 1, 2025, CMS-3355-F was the first major update to CLIA PT regulations since 1992. It added 29 newly regulated analytes, removed five, revised grading criteria and acceptance limits, and clarified how PT referral provisions apply to laboratories performing waived testing. Laboratories should reconcile their current enrollment against the updated analyte list and confirm the new acceptance limits with their PT provider.

Why is referring a PT sample to another laboratory so serious?

PT referral is the single most severely penalized error in CLIA. Under 42 CFR 493.1840, an intentional PT referral can lead to revocation of the CLIA certificate for at least one year and a ban on the owner and operator from owning or operating any CLIA-certified laboratory for at least a year, plus possible civil money penalties for the most serious cases. Most referrals happen by accident through send-out or reflex workflows, which is why a written no-referral procedure and trained staff are essential.

What happens if my laboratory fails a proficiency testing event?

A single failed event is unsatisfactory performance and requires investigation, root-cause analysis, and documented corrective action. Failing the same analyte in two consecutive events, or two of three consecutive events, is unsuccessful performance, which directs the laboratory to cease testing for that analyte until it corrects the problem and completes two consecutive successful PT events to be reinstated. A cease-testing order can also suspend Medicare and Medicaid payment for the affected testing.

How can LMC help my laboratory build a compliant PT program?

LMC reviews your enrollment against the current regulated-analyte list, develops PT handling and referral-prevention procedures tailored to your menu, builds the safeguards that prevent accidental referral, supports corrective action when an event fails, and provides ongoing laboratory director oversight.

Protect Your CLIA Certificate

Proficiency testing is where CLIA compliance is won or lost. A program that matches your test menu, prevents accidental referral, and documents every event protects your certificate, your reimbursement, and the trust physicians place in your results.

Contact Laboratory Management Consultants today at (606) 487-0523 or email tpace@emaillmc.com for a free consultation on your proficiency testing program.

Visit us online at https://laboratorymanagementconsultants.org to learn more about our flexible laboratory consulting, director services, and compliance support.

Whether your laboratory is enrolling for the first time, reconciling its menu against the 2022 Final Rule, or recovering from a failed event, the right PT program keeps you in good standing and your patients well served.