Modifier QW- CLIA Waived Test

Identifies certain laboratory tests classified as waived under the Clinical Laboratory Improvement Amendments when the QW modifier is required for Medicare claim processing.

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What Is Modifier QW?

Modifier QW is a HCPCS Level II modifier defined as CLIA waived test.

It is appended to certain laboratory procedure codes to indicate that the test is classified as waived under the Clinical Laboratory Improvement Amendments (CLIA).

CLIA establishes federal quality standards for laboratory testing. Laboratories must hold the appropriate CLIA certificate for the testing they perform. A laboratory operating under a Certificate of Waiver may perform tests categorized as waived. CMS states that all CLIA certificate types permit waived testing.

QW is important for Medicare claim processing because some waived tests must be submitted with the modifier for Medicare to recognize the procedure as a CLIA-waived test.

However, not every waived laboratory test requires QW. CMS maintains specific HCPCS codes that are recognized as waived without the modifier.

When to Use Modifier QW

CLIA-Waived Test: The laboratory test performed has been categorized as waived under CLIA.

QW Required for the Code: CMS requires QW with the specific CPT or HCPCS code for the test to be recognized as waived.

Certificate of Waiver Laboratory: The testing facility operates under a CLIA Certificate of Waiver and performs a qualifying waived test.

Other Qualified CLIA Laboratory: A laboratory holding another CLIA certificate may also perform waived testing because all CLIA certificate types allow waived tests.

Current CMS Waived-Test List: The particular test and procedure code appear in current CMS guidance as requiring QW.

Point-of-Care Testing: QW may be required for qualifying waived tests performed in physician offices and other point-of-care settings when the specific test and code meet CMS requirements.

When NOT to Use Modifier QW

Non-Waived Test: Do not append QW to moderate- or high-complexity testing simply because the laboratory performs other waived tests.

Code Does Not Require QW: Some procedure codes are recognized by Medicare as waived tests without QW. CMS specifically notes that some waived tests have unique HCPCS codes while others require QW.

Test Is Not CLIA-Waived: The actual test system must qualify as waived. QW cannot be used to convert a non-waived test into a waived test.

Laboratory Lacks Appropriate CLIA Certification: QW does not replace the requirement for the testing site to maintain appropriate CLIA certification.

To Obtain Payment: QW identifies the waived status of an applicable test. It does not independently establish Medicare coverage or medical necessity.

Incorrect Test Method: A procedure code may encompass testing performed using different methodologies or systems. QW should only be used when the actual test performed qualifies as waived under current requirements.

Billing Example

A physician-office laboratory performs a laboratory test using an FDA-approved test system categorized as CLIA waived.

The laboratory holds an appropriate CLIA certificate, and CMS requires the applicable procedure code to carry QW for the test to be recognized as waived.

The claim is submitted using the applicable laboratory procedure code with Modifier QW.

QW tells Medicare that the reported test was performed using a qualifying CLIA-waived methodology.

CMS continues to use this reporting structure in 2026. For example, CMS clarified that HCPCS G0567 is payable with QW when performed by a CLIA-waived laboratory and without QW when performed by a non-CLIA-waived laboratory.

Documentation Requirements

Test Performed: Document the specific laboratory test performed.

Test System: Maintain information identifying the test system or methodology used when necessary to establish waived status.

CLIA Certification: The testing location must maintain the appropriate CLIA certificate for the testing performed.

CLIA Number: Report the laboratory's CLIA number on Medicare claims when required.

Test Results: Maintain the patient's test results as part of the laboratory or medical record.

Medical Necessity: When Medicare coverage depends on medical necessity, documentation should support why the laboratory test was ordered and performed.

Current Waived Status: Confirm that the test system and procedure code qualify for waived reporting for the applicable date of service.

Billing and Claim Considerations

Modifier QW does more than indicate that a laboratory test is relatively simple to perform. It has a specific role within Medicare's CLIA claim-editing system.

CMS states that claims for laboratory tests subject to CLIA are edited at the CLIA certificate level. CMS also updates the codes subject to CLIA requirements as laboratory tests and classifications change.

For some waived tests, the procedure code alone identifies the test as waived. For others, QW must accompany the CPT or HCPCS code.

This makes code-specific verification important.

Providers should verify the current CMS CLIA waived-test information rather than assuming that every waived test requires QW.

CMS continues to publish quarterly Clinical Laboratory Fee Schedule and CLIA updates. The July 2026 update included HCPCS codes and waived-test changes, and CMS issued another CLFS/CLIA quarterly update for October 2026.

QW and CLIA Certificates

A CLIA Certificate of Waiver allows a laboratory to perform tests categorized as waived.

CMS currently identifies several types of CLIA certificates, and all certificate types permit laboratories to perform waived testing.

This means QW is not limited exclusively to laboratories holding a Certificate of Waiver.

Instead, the modifier identifies the waived status of the applicable test when QW is required for that procedure code.

The laboratory must still operate within the testing complexity permitted by its CLIA certification.

Not Every Waived Test Requires QW

One of the most important QW billing distinctions is that CLIA-waived does not automatically mean QW must appear on the claim.

CMS explains that some waived tests have procedure codes that inherently identify them as waived, while other tests require QW to establish their waived status for claims processing.

CMS has historically maintained specific exceptions to QW reporting and updates its waived-test information as new tests receive waived status.

Therefore, providers should verify the specific procedure code and test system before submitting QW.

Modifier QW vs. Modifier 90

Modifier QW: Identifies an applicable laboratory test as CLIA waived.

Modifier 90: Identifies a laboratory test referred to an outside laboratory for performance.

These modifiers describe entirely different circumstances.

QW addresses test complexity and CLIA status, while Modifier 90 identifies who performed the laboratory test.

A test being performed by an outside reference laboratory does not automatically make it waived, and a waived test does not automatically qualify for Modifier 90.

Modifier QW vs. Modifier 92

Modifier QW: Identifies a qualifying CLIA-waived laboratory test.

Modifier 92: Identifies qualifying testing performed using an alternative laboratory platform.

The modifiers are not interchangeable.

QW communicates the test's CLIA-waived status when required. Modifier 92 describes a particular testing platform circumstance and has separate reporting requirements.

Providers should select modifiers according to the actual test, methodology, and applicable payer instructions.

Common Billing Mistakes

Appending QW to Every Waived Test: Some waived tests do not require QW because their procedure codes already identify them as waived.

Missing QW When Required: A qualifying waived test may fail Medicare's CLIA edits when QW is required but omitted.

Using QW for a Non-Waived Test: QW cannot change the CLIA complexity classification of a laboratory test.

Ignoring the Specific Test System: Different testing systems reported under a procedure code may have different CLIA classifications.

Incorrect CLIA Certification: The laboratory must hold certification appropriate for the testing it performs.

Using Outdated Waived-Test Information: CMS updates CLIA-waived test information as new tests and codes become available. CMS continued issuing quarterly CLIA updates in 2026.

Common Denial Reasons

QW Modifier Missing: The procedure requires QW to be recognized as a waived test, but the modifier was omitted.

Test Not Recognized as Waived: The reported test or methodology does not qualify for CLIA-waived status.

CLIA Certificate Mismatch: The laboratory's certification does not support the complexity of the test performed.

Invalid or Missing CLIA Information: Required CLIA identifying information is absent or incorrect on the claim.

Incorrect Procedure Code: The reported CPT or HCPCS code does not accurately represent the test performed.

Medical Necessity Not Supported: The laboratory test does not satisfy applicable Medicare coverage requirements even though the test itself is CLIA waived.

Frequently Asked Questions

Does every CLIA-waived test require Modifier QW?
No. CMS states that some waived tests have unique procedure codes that identify them as waived without QW, while other waived tests require QW with the procedure code. The current CMS waived-test information should be checked for the specific test.

Does Modifier QW mean a laboratory test is automatically covered by Medicare?
No. QW identifies applicable testing as CLIA waived for claim-processing purposes. The test must still satisfy Medicare coverage, coding, medical-necessity, and other applicable billing requirements.