What Is CLIA? Clinical Laboratory Improvement Amendments Explained

Q: Does my physician office or clinic need a CLIA certificate?

Yes, if you perform any testing on human specimens, even a single test. The rule under CLIA is that if a facility performs even one test on human samples to assess health or to diagnose, prevent, or treat disease, it is considered a laboratory and must apply for a CLIA certificate. A physician office that performs only simple tests like urine dipstick or blood glucose can apply for a Certificate of Waiver, which carries the least regulatory burden. A physician office performing microscopy can apply for a PPM certificate.

Q: What happens if a laboratory fails a proficiency test under CLIA?

Unsatisfactory proficiency testing performance triggers a required remedial action. The laboratory must identify the cause of the failure, correct it, and document the steps taken. If a laboratory has unsuccessful participation, defined as unsatisfactory performance for the same analyte in two consecutive testing events or two out of three events, CMS may impose sanctions. The most serious sanction is suspension of the laboratory's CLIA certificate, which prohibits it from testing patient specimens until compliance is restored.

By the NPI Profile Editorial Team Last updated: June 26, 2026 Based on official CMS, CDC, and FDA documentation

Quick Answer

CLIA, or the Clinical Laboratory Improvement Amendments, is a federal law passed in 1988 that requires almost every facility in the United States that tests human blood, tissue, or body fluid to hold a valid certificate from CMS. The law sets quality standards that are scaled to the complexity of the testing being performed: the more difficult the test, the stricter the requirements. Approximately 320,000 laboratories are currently regulated under CLIA. If a lab performs even a single test on a human specimen for diagnostic or treatment purposes, it needs a CLIA certificate, with a small number of specific exceptions.^[1]

Background and Purpose

Before CLIA, the quality of clinical laboratory testing in the United States varied widely. A 1987 cytology proficiency study revealed alarming error rates in Pap smear interpretation at some labs, which drew Congressional attention and led directly to the law that followed. Congress passed the Clinical Laboratory Improvement Amendments of 1988 (Public Law 100-578) to establish uniform federal standards for all laboratories testing human specimens, regardless of where those tests are performed or who performs them.

The core objective is patient safety. Accurate laboratory results are essential for correct diagnoses and treatment decisions, and errors in testing can lead to missed diagnoses, unnecessary treatments, or delayed care. CLIA ensures that applicable laboratories meet minimum standards to conduct testing that is accurate, reliable, and timely.^[1]

The law is formally codified at 42 USC 263a and implemented through the federal regulations at 42 CFR Part 493. Amendments were made in 1988, 1997, and 2012, but the law continues to be cited as CLIA '88. Final CLIA regulations were published in 1992, phased in through 1994, and further amended in 1993, 1995, and 2003.^[2]

Who Administers CLIA: CMS, CDC, and FDA

Three federal agencies share responsibility for the CLIA program, each with a defined role.

CMS (Centers for Medicare and Medicaid Services) has primary regulatory authority. CMS issues CLIA certificates, sets quality standards, oversees laboratory surveys, and enforces compliance. CMS processes applications through State Agencies, which serve as the ground-level administrative and inspection arm for CLIA in each state.^[1]

CDC (Centers for Disease Control and Prevention) provides scientific support. CDC's responsibilities include providing analysis, research, and technical assistance; developing technical standards and laboratory practice guidelines including cytology standards; conducting laboratory quality improvement studies; monitoring proficiency testing practices; and managing the Clinical Laboratory Improvement Advisory Committee (CLIAC).^[2]

FDA (Food and Drug Administration) categorizes tests by complexity. Since November 2003, FDA has had authority to categorize in vitro test systems by complexity level (waived, moderate, or high). The FDA CLIA database contains all commercially marketed test systems categorized since January 2000. When a laboratory wants to know whether a specific test is waived or nonwaived, the FDA database is the authoritative source.^[3]

Who Needs a CLIA Certificate

The scope of CLIA is intentionally broad. Any facility or site that performs testing on human specimens for health assessment or to diagnose, prevent, or treat disease is considered a laboratory under CLIA and must hold the appropriate certificate before accepting specimens for testing. This covers far more than traditional hospital or independent laboratories.

The following facility types are among those that commonly hold CLIA certificates:

Hospital laboratories
Independent clinical laboratories
Physician office laboratories (including solo practices that perform only a glucose finger stick)
Community health clinics and Federally Qualified Health Centers
Ambulatory surgery centers performing pre-operative testing
Skilled nursing facilities and assisted living facilities
Home health agencies that perform point-of-care testing
End stage renal disease dialysis facilities
Pharmacies that offer testing services
Schools and student health clinics
Correctional facilities
Mobile laboratories and health fair testing sites
Blood banks
Public health laboratories

The key threshold is whether a test result will be reported for the purpose of diagnosis or treatment. A physician office that tests a urine sample to help diagnose a urinary tract infection meets that threshold and needs a CLIA certificate, even if the only test performed is a simple dipstick.^[1]

Exemptions: Who Does Not Need a CLIA Certificate

Three categories of testing are exempt from CLIA requirements regardless of where the laboratory is located:

Laboratories that perform testing only for forensic purposes, such as criminal investigations.
Research laboratories that test human specimens but do not report patient-specific results for clinical diagnosis or treatment decisions. If the results are used only for research or population surveillance and are never used for individual patient care, CLIA does not apply.
SAMHSA-certified laboratories when performing only employment-related drug testing. If a SAMHSA-certified laboratory performs any other testing on human specimens, CLIA certification is required for that additional testing.

Two states have their own HHS-approved laboratory regulatory programs that may substitute for the federal CLIA program. Laboratories in New York (with a partial exemption) and Washington state should contact their State Agency directly to determine whether they need a federal CLIA certificate in addition to their state permit.^[1]

International laboratories

Laboratories located outside the United States that want to test specimens from U.S. patients can apply for CLIA certification. International applicants must contact CMS at [email protected] before completing the standard CMS-116 application, as a separate international laboratory process applies.

How CLIA Defines Test Complexity

CLIA requirements are not one-size-fits-all. The regulatory burden placed on a laboratory is scaled to the complexity of the testing it performs. In general, the more complicated the test, the more stringent the requirements. Understanding the three complexity levels is essential because they determine which CLIA certificate a laboratory needs and what quality standards apply.

Complexity level	What it means	Example tests	Certificate required
Waived	Simple tests with a low risk of producing an incorrect result. FDA approves waiver applications submitted by manufacturers. Follows only manufacturer instructions; most CLIA quality requirements do not apply.	Urine dipstick, blood glucose meters, home pregnancy tests used in a clinical setting, rapid influenza tests, rapid strep tests	Certificate of Waiver (CoW)
Moderate complexity	Requires minimal scientific and technical knowledge. More quality control, personnel, and documentation requirements than waived testing. PPM procedures fall within this category.	Urinalysis with microscopy, routine hematology, basic metabolic panel on automated analyzers, most routine chemistry testing	PPM (microscopy only) or CoC / CoA
High complexity	More difficult to perform or interpret than waived and moderate tests. Specialized scientific knowledge and training are required. Strictest personnel, QC, and proficiency testing requirements apply.	Cytology (Pap smears), histopathology, blood typing and crossmatching, advanced molecular diagnostics, cytogenetics	CoC or CoA

The FDA CLIA database at accessdata.fda.gov is the definitive reference for determining a specific test's complexity category. When a laboratory cannot find a test in the FDA database, the State Agency can assist with categorization.

The Five CLIA Certificate Types

A laboratory's certificate type must correspond to the highest level of test complexity it performs. All certificates are valid for two years. All certificate types permit waived testing, but a laboratory holding only a Certificate of Waiver may not perform moderate or high complexity testing without upgrading its certificate type first.^[4]

Certificate of Waiver (CoW)

Issued to laboratories that perform only waived tests. The CoW carries the least regulatory burden: the laboratory must follow the manufacturer's instructions for each waived test and pay the biennial certificate fee, but most of the quality system requirements, proficiency testing requirements, and personnel standards that apply to nonwaived testing do not apply. Laboratories with a CoW are not routinely surveyed, though an unannounced onsite survey may occur if CMS or a State Agency receives a complaint.

A physician office that offers only a rapid strep test and a urine dipstick would hold a CoW. If that office later wants to add a test that is categorized as moderate complexity, it must upgrade to a PPM or nonwaived certificate before adding the new test to its menu.

Certificate for Provider Performed Microscopy Procedures (PPM)

A limited certificate issued to laboratories in which a physician, mid-level practitioner (nurse midwife, nurse practitioner, nurse anesthetist, clinical nurse specialist, or physician assistant), or dentist performs specific microscopy procedures personally during a patient's visit. PPM procedures are categorized as moderate complexity testing but fall under a defined list, not all moderate complexity testing.

The PPM certificate applies only when the practitioner themselves performs the microscopy. A lab technician performing microscopy in the same setting is not covered under PPM and requires a nonwaived certificate. Like CoW laboratories, PPM labs are not routinely surveyed. A CMS-published list of PPM procedures identifies exactly which tests qualify.

Certificate of Registration (CoR)

A temporary certificate issued to laboratories that are applying for a Certificate of Compliance or Certificate of Accreditation. The CoR allows the laboratory to perform nonwaived testing while it awaits its initial compliance survey. It is valid for no more than two years. Once the initial survey is conducted and the laboratory is determined to be in compliance, the CoR is replaced by a CoC or CoA.

Laboratories applying only for a Certificate of Waiver or PPM do not receive a CoR; the CoR is exclusively a transitional certificate for laboratories entering the nonwaived testing pathway.

Certificate of Compliance (CoC)

Issued to laboratories that perform nonwaived moderate and/or high complexity testing after CMS or a State Agency surveyor conducts an onsite survey and determines that the laboratory is in compliance with all applicable CLIA requirements. Laboratories with a CoC are surveyed every two years. If deficiencies are found during a survey, the CoC is not renewed until the laboratory corrects the deficiencies and demonstrates compliance.

Fees for CoC laboratories include a one-time registration fee (which triggers issuance of a CoR), a compliance survey fee covering the survey cost, and a compliance certificate fee once compliance is confirmed. Every two years the cycle repeats.

Certificate of Accreditation (CoA)

Issued to laboratories that perform nonwaived testing and choose to be accredited by a CMS-approved Accreditation Organization (AO) rather than be inspected directly by CMS or a State Agency. Accredited laboratories are still subject to CLIA requirements but are surveyed by their AO instead of by a government surveyor. A limited percentage of CoA laboratories receive a CMS validation survey to ensure the AO's assessment aligns with CLIA standards.

There are currently seven CMS-approved AOs: the Association for the Advancement of Blood and Biotherapies (AABB), the American Association for Laboratory Accreditation (A2LA), the Accreditation Commission for Health Care (ACHC), the American Society for Histocompatibility and Immunogenetics (ASHI), the Commission on Laboratory Accreditation (COLA), the College of American Pathologists (CAP), and The Joint Commission. AO requirements may be more stringent than the federal CLIA minimum standards.

How to Apply for CLIA Certification

CLIA certification follows a five-step process. Applications are submitted to the State Agency in the state where the laboratory is located, not directly to CMS, with the exception of the international laboratory pathway.^[4]

Complete Form CMS-116, the CLIA Application for Certification.
This fillable PDF form is available on the CMS website. Section II requires selecting the certificate type that corresponds to the highest level of test complexity the laboratory will perform. Section III identifies the type of laboratory (physician office, hospital, independent, etc.). All sections must be completed; CMS cannot process incomplete applications. For PPM, CoC, and CoA applications, documentation of the laboratory director's qualifications must be submitted with the form.
Submit the completed application to the State Agency.
Send the CMS-116 and any required supporting documents to the State Agency for the state where the laboratory is physically located. Some states have additional state-specific requirements beyond the federal CMS-116. Check with the State Agency before submitting to avoid delays. Laboratories in New York and Washington state should contact those State Agencies for guidance before completing the standard form.
Receive the fee coupon and pay the CLIA certification fee.
After the State Agency processes the application, the laboratory receives a fee coupon by email. The coupon contains the laboratory's unique 10-character alphanumeric CLIA identification number. Fees are paid at pay.gov and vary by certificate type and, for nonwaived certificates, by test volume. CMS accepts bank account (ACH), debit, and credit card payments.
Receive the CLIA certificate and begin testing.
The CLIA certificate arrives by email after payment is received. Testing may begin once the certificate is in hand. Laboratories applying for a CoC or CoA receive a CoR at this stage and may begin nonwaived testing under the CoR while awaiting their initial survey. Laboratories should check with the State Agency since some states have additional requirements that must be met before testing begins.
Maintain the certificate through biennial renewal and compliance.
All CLIA certificates are valid for two years. CoW and PPM laboratories receive a renewal invoice six months before expiration. CoC laboratories receive a compliance survey every two years; CoA laboratories are surveyed by their AO on a similar cycle. Any changes in laboratory ownership, name, location, or director must be reported to the State Agency within 30 days for all certificate types. Changes in testing scope must be reported immediately for CoW and PPM laboratories, or within six months for nonwaived certificates.

Maintaining a CLIA Certificate: Surveys and Required Notifications

Once a laboratory holds a CLIA certificate, it has ongoing obligations that extend well beyond paying renewal fees. The most significant distinction is whether the laboratory is subject to routine surveys.

Certificate type	Routine survey schedule	Notification deadlines
Certificate of Waiver (CoW)	Not routinely surveyed. Unannounced survey may occur on complaint.	Ownership, name, location, director: 30 days. New test added outside waived category: immediately (before testing).
PPM	Not routinely surveyed. Unannounced survey may occur on complaint.	Ownership, name, location, director: 30 days. New test outside PPM scope: immediately (before testing).
Certificate of Compliance (CoC)	Every 2 years by CMS or State Agency.	Ownership, name, location, director, technical supervisor: 30 days. Changes in specialties or test methodology: within 6 months.
Certificate of Accreditation (CoA)	Every 2 years by the CMS-approved AO. A percentage of CoA labs receive a CMS validation survey.	Ownership, name, location, director: notify State Agency within 30 days and AO within 6 months. Changes in specialties or test methodology: notify AO within 6 months.

Testing outside your certificate scope requires notification before you start

A laboratory with a Certificate of Waiver that wants to add a moderate complexity test cannot begin that testing until it has notified the State Agency and received an updated certificate. CoW and PPM laboratories must notify their State Agency immediately, before adding any test outside their current certificate scope. For laboratories applying to upgrade from CoW to a nonwaived certificate, the CoR issued by CMS authorizes the new testing while the initial survey is pending.^[4]

Proficiency Testing Requirements

Proficiency testing (PT) is the primary mechanism CLIA uses to verify that a laboratory's test results are accurate and consistent with results from other laboratories. A HHS-approved PT program sends test samples to the laboratory, the laboratory tests them as it would patient specimens, and reports the results back to the PT program, which grades them against established criteria. CMS and accreditation organizations monitor PT scores on an ongoing basis.^[5]

PT is required for nonwaived testing of regulated analytes listed in Subpart I of the CLIA regulations. Waived testing does not require PT, though enrolling in a PT program voluntarily for waived tests is considered good laboratory practice. For unregulated analytes that are not on the Subpart I list but are still nonwaived, laboratories must verify accuracy at least twice per year by an alternate method, such as split-specimen comparison with another laboratory.

Several PT rules have practical implications that laboratories frequently overlook:

PT samples must be tested exactly as patient specimens are tested, by the same personnel, using the same instruments and reagents, and in the same number of replicates.
PT samples must never be sent to another laboratory for testing, even if the laboratory would routinely refer that type of specimen. PT referral is a sanctionable offense and can result in certificate suspension.
A laboratory may not change from one approved PT program to another during its first year of enrollment. Changes require prior notification to CMS.
Unsuccessful PT participation, defined as unsatisfactory performance for the same analyte in two consecutive events or two out of three events, triggers mandatory remedial action and may result in CMS sanctions.^[5]

CLIA and the NPI: How They Connect

CLIA and the NPI registry are two separate federal systems, but they overlap in meaningful ways for laboratories and the professionals who work with laboratory data.

Many laboratories hold both an NPI and a CLIA number. The NPI is a HIPAA identifier used for billing and health information transactions. The CLIA number is a quality regulation identifier confirming the laboratory is certified to perform clinical testing. The two numbers serve different regulatory purposes and are issued by different programs, but laboratories billing Medicare for their testing services need both: the NPI for the billing transaction and the CLIA certificate as the underlying qualification for the services billed.

NPI Profile's CLIA crosswalk tool connects these two identifiers. You can search by an NPI number to find the associated CLIA number for a laboratory provider, or search by CLIA number to retrieve the corresponding NPI record. This is particularly useful for billing staff verifying that a laboratory they are billing for holds a current CLIA certificate, and for credentialing specialists confirming a laboratory's certification status.

Look up any laboratory's CLIA certification by NPI number or CLIA number. NPI Profile's CLIA crosswalk tool searches both identifiers in one place.

CLIA Lookup

The official CMS laboratory registry is available through the Quality, Certification and Oversight Reports (QCOR) system at qcor.cms.gov. QCOR allows searching by CLIA number, facility name, address, certificate type, and geographic area. It also provides access to a laboratory's most recent electronic CLIA certificate. The CDC retired its own CLIA Laboratory Search tool in January 2024, so the CMS QCOR system is now the primary government lookup source.

Frequently Asked Questions

What does CLIA stand for and what does it regulate?

CLIA stands for Clinical Laboratory Improvement Amendments. It is a federal law that establishes quality standards for virtually all laboratory testing performed on human specimens in the United States. Any facility that tests human blood, tissue, or body fluid to diagnose, prevent, or treat disease is considered a laboratory under CLIA and must hold the appropriate certificate before accepting specimens. The law is implemented primarily by CMS, with roles shared by CDC and FDA.^[1]

Who is exempt from CLIA?

Three categories of testing are exempt from CLIA regardless of location: laboratories testing only for forensic purposes; research laboratories that test human specimens but do not report patient-specific results for diagnosis or treatment; and SAMHSA-certified laboratories performing only employment-related drug testing. Laboratories in New York and Washington state may not need a federal CLIA certificate because those states operate their own HHS-approved programs.^[1]

What are the five CLIA certificate types?

The five CLIA certificate types are: Certificate of Waiver (CoW) for labs performing only simple waived tests; Certificate for Provider Performed Microscopy Procedures (PPM) for physicians, mid-level practitioners, or dentists performing specific microscopy procedures during patient visits; Certificate of Registration (CoR) a temporary certificate while a lab awaits its initial compliance survey; Certificate of Compliance (CoC) issued after a government survey confirms compliance; and Certificate of Accreditation (CoA) issued through a CMS-approved Accreditation Organization. All certificates are valid for two years.^[4]

What is a CLIA number and how do I look it up?

A CLIA number is the unique 10-character alphanumeric identifier assigned to a laboratory when it applies for CLIA certification. The first two characters encode the laboratory's state. You can look up any CLIA-certified laboratory using NPI Profile's CLIA crosswalk tool, which searches by NPI number, CLIA number, or provider name. The official CMS lookup is the QCOR system at qcor.cms.gov.

Does my physician office or clinic need a CLIA certificate?

Yes, if you perform any testing on human specimens. Under CLIA, if a facility performs even one test on human samples to assess health or to diagnose, prevent, or treat disease, it is considered a laboratory and must apply for a certificate. A physician office performing only simple tests like a urine dipstick or blood glucose check can apply for a Certificate of Waiver, which carries the least regulatory burden. An office performing microscopy can apply for a PPM certificate.^[1]

What happens if a laboratory fails a proficiency test under CLIA?

Unsatisfactory PT performance requires mandatory remedial action: identify the cause, correct it, and document the steps taken. Unsuccessful PT participation, defined as unsatisfactory performance for the same analyte in two consecutive testing events or two out of three events, may result in CMS sanctions. The most serious sanction is suspension of the laboratory's CLIA certificate, which prohibits patient specimen testing until compliance is restored. PT referral, sending PT samples to another laboratory, is a separately sanctionable offense.^[5]

Sources

This article is based on the following official government publications. NPI Profile summarizes official documentation for convenience; source documents remain the authoritative reference. State, local, and accreditation requirements may be more stringent than the federal CLIA minimum standards described here.

Centers for Medicare and Medicaid Services. Clinical Laboratory Improvement Amendments (CLIA) Certification (CMS CLIA Certification Brochure, revised March 2026). Scope of CLIA, the definition of a laboratory under 42 CFR 493.3, exemptions for forensic and research testing and SAMHSA-certified labs, New York and Washington state exemptions, the rule that even one test triggers CLIA certification, the 320,000 lab count, and the five certificate types.
Centers for Disease Control and Prevention. Clinical Laboratory Improvement Amendments (CLIA): Background and Responsibilities. CDC CLIA program overview page. Statutory history (Public Law 100-578, 1967 and 1988 laws, 1997 and 2012 amendments), codification at 42 USC 263a, the 42 CFR Part 493 implementing regulations, CDC responsibilities within the three-agency structure, and CLIAC.
Centers for Medicare and Medicaid Services. CLIA Accreditation and Testing: Categorization of Tests. CMS CLIA accreditation page. FDA authority over test complexity categorization since November 2003, the FDA CLIA database for commercially marketed in vitro test systems, and the three-agency administrative structure.
Centers for Medicare and Medicaid Services. CLIA Certification Quick Start Guide (March 2026) and How to Apply for a CLIA Certificate, Including International Laboratories. CMS.gov. The five-step certification process, Form CMS-116 instructions, certificate type selection by test complexity, CoR as transitional certificate, the seven CMS-approved AOs, survey schedules by certificate type, the 30-day notification requirements, the change-of-testing notification rules, and fee structures by certificate type.
Centers for Medicare and Medicaid Services. CLIA Proficiency Testing and PT Referral (revised October 2024). Proficiency testing requirements under Subpart I, HHS-approved PT program enrollment, the three-events grading cycle, the definition of unsuccessful participation, PT referral prohibition and sanctions, and the twice-yearly accuracy verification requirement for unregulated nonwaived analytes.