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CLIA (Clinical Laboratory Improvement Amendments) - Federal Regulation

The Clinical Laboratory Improvement Amendments (CLIA) has established quality standards for all laboratory testing to ensure the accuracy, reliability and timeliness of patient test results regardless of where the test is performed. Under CLIA, a laboratory is defined as a facility that performs testing on human specimens for the purpose of providing information for diagnosis, prevention, treatment of disease or health assessment. Facilities, including physician office practices, that meet this definition must apply and obtain a certificate from the CLIA program to operate legally.

The CLIA regulations place tests in three categories based on the complexity of each test. The more complicated the test, the more stringent the applicable federal requirements. The categories are as follows:

Waived Tests

These laboratory tests are so simple and accurate that the likelihood of erroneous results is negligible and they pose no reasonable risk of harm to the patient if performed incorrectly. The law specifies that waived tests are exempt from the CLIA health and safety standards, including personnel, patient test management, quality control, proficiency testing, quality assurance and routine inspection requirements. Office practices or facilities performing waived tests must enroll in the CLIA program and obtain a Certificate of Waiver (COW). A COW is required regardless of the number of tests that are performed even if the patient, Medicare or other insurances are not charged or billed. Manufacturers' instructions for the waived tests must be followed. Laboratories with COWs will not be inspected routinely; however, they may be inspected as part of complaint investigations and on a random basis to determine whether only the waived tests are being performed. A full listing of waived tests can be found at

Practices performing waived tests should have a policy and process in place for quality control testing. At a minimum, quality controls should be performed with each new shipment of kits/reagents, a change in lot numbers and each new operator. Quality control results should be tracked and action should be taken when controls give unexpected results. Actions taken as a result of unexpected results should be documented.

Moderate Complexity Tests

These tests are more complex than waived tests and much of the testing performed in clinical laboratories falls into this category. There are requirements for quality control, quality assurance, proficiency testing and limited personnel requirements. A laboratory performing this level of testing is subject to biennial surveys by the Center for Medicare and Medicaid Services (CMS) or a CMS agent. Examples of moderate complexity tests are microscopic analysis of urinary sediment, some direct antigen strep A tests, cervical and urethral Gram stains and some hematology and chemistry tests.

  • Provider-performed microscopy (PPM) is a subcategory of moderately complex procedures and applies to certain tests commonly performed under a microscope in the provider's office during the course of a patient's visit. A physician, midlevel practitioner or dentist can perform this limited number of tests once a Certificate for Provider Performed Microscopy is obtained. Sites performing PPM tests are subject to the same requirements as moderately complex laboratories, except that they will not be inspected and need only do proficiency testing if programs are available. A list of PPM procedures is available at

High Complexity Tests

These are tests that are most difficult to perform or are most subject to error. They are usually performed only by large clinical laboratories and require quality control, quality assurance, proficiency testing and stricter personnel requirements. The major differences in requirements between moderate and high complexity testing is in quality control and personnel standards. Laboratories performing high complexity tests are subject to biennial surveys by CMS or a CMS agent. To determine which tests are categorized as high complexity, moderate complexity or waived, refer to

Facilities performing moderate (excluding PPM) and/or high complexity testing must apply for a Certificate of Compliance (COC) or Certificate of Accreditation (COA). The COC is issued when an inspection, conducted by the appropriate State authority, determines that the laboratory is compliant with all applicable CLIA requirements. Alternatively, a COA is issued when a CMS approved accreditation organization determines the laboratory's compliance with accreditation standards. Each facility must first apply for a Certificate of Registration to allow it to perform moderate and/or high complexity tests pending a certification inspection. If a facility wishes to add testing of a higher complexity not covered under their current certificate, it must re-apply for the appropriate certificate. Waived tests can be performed with any certificate.

Certification for all waived and non-waived testing is issued on a two-year basis.

CMS is responsible for implementation of CLIA, including registration, fee collection, surveys and enforcement. The Centers for Disease Control and Prevention (CDC) provides scientific and technical support and consultation to CMS. The Food and Drug Administration (FDA) is responsible for test categorization.

The CMS survey process is outcome oriented, focusing on quality and education as the best tools to assess compliance. Available data indicates that CLIA has contributed to an improved quality of testing in the United States. Further information about CLIA can be accessed at or by contacting your local state survey agency. The agencies for Maine, New Hampshire, Vermont and Massachusetts are listed below.


CLIA Program
Division of Licensing & Regulatory Services
41 Anthony Avenue, Station #11
Augusta, Maine 04330-0011
Fax: 207-287-9304

New Hampshire and Vermont

Health Facilities Administration
Department of Health & Human Services
129 Pleasant Street
Concord, NH 03301
603- 271- 9048
Fax: 603-271-4968


CDC Booklet: To Test or Not to Test-Considerations for Waived Testing
CDC Booklet: Ready, Set, Test