Modifier QW is a HCPCS Level II modifier that identifies a Clinical Laboratory Improvement Amendments (CLIA) waived laboratory test.

Under the Clinical Laboratory Improvement Amendments of 1988 (CLIA), laboratory tests are categorized according to their complexity:

Waived tests
Moderate complexity tests
High complexity tests

Modifier QW tells Medicare that the laboratory test being billed is a CLIA-waived test performed by a provider holding an appropriate CLIA certificate.

This modifier is frequently used by:

Physician offices
Urgent care centers
Rural health clinics
Federally Qualified Health Centers
Independent laboratories
Retail clinics
Ambulatory care centers

CMS issues periodic updates whenever the FDA approves additional waived tests that require the QW modifier.

Modifier

Modifier Name

CLIA Waived Test

Plain English Explanation

Modifier QW tells Medicare:

“This laboratory test is classified as a CLIA-waived test and was performed by a provider authorized to perform waived testing.”

Purpose

Modifier QW is used to:

Identify CLIA-waived laboratory testing.
Ensure Medicare processes eligible waived laboratory claims correctly.
Distinguish waived tests from moderate- or high-complexity laboratory testing.
Verify compliance with CLIA certification requirements.

Understanding Modifier QW

CLIA regulations classify laboratory testing according to complexity.

Waived tests are:

Simple to perform.
Low risk for erroneous results.
FDA-approved as waived under CLIA.
Commonly performed at the point of care.

Examples include:

Rapid strep tests
Influenza tests
COVID-19 antigen tests (when applicable)
Urine pregnancy tests
Certain glucose tests
Fecal occult blood tests
Mononucleosis tests

Some CPT codes always require Modifier QW, while other CPT codes are inherently recognized as waived and do not require QW. CMS publishes and updates these lists regularly.

When to Use Modifier QW

Append Modifier QW when:

The laboratory test is designated by CMS as requiring QW.
The provider has an appropriate CLIA Certificate (or higher-level CLIA certification that includes waived testing).
Medicare requires QW recognition for the specific CPT/HCPCS code.
The service is performed in accordance with CLIA requirements.

Examples of commonly reported QW-required laboratory codes (depending on CMS/FDA updates):

CPT Code	Description
87880	Rapid Streptococcus test
87804	Influenza virus test
86308	Mononucleosis test (certain FDA-waived methods)
80305	Drug screening (specific FDA-waived devices)
87801	Certain molecular infectious disease tests (specific FDA-waived devices)

Note: Whether QW is required depends on the specific FDA-cleared device and current CMS instructions. CMS updates the list whenever new waived tests are approved.

When NOT to Use Modifier QW

Do not use Modifier QW when:

The laboratory test is moderate or high complexity.
The CPT code is one of the codes CMS recognizes as waived without requiring QW (for example, certain longstanding waived codes such as 81025, 82962, and others identified by CMS).
The provider does not possess the appropriate CLIA certification.
The payer specifically instructs not to append QW.

Medicare Rules

Medicare requires:

An appropriate CLIA certificate before performing waived laboratory testing.
Modifier QW for many—but not all—waived laboratory CPT/HCPCS codes.
The provider’s CLIA number on the claim when required.
CMS periodically updates the list of FDA-approved waived tests requiring Modifier QW.

Importantly, CMS also maintains a list of CPT codes that are automatically recognized as waived and therefore do not require Modifier QW (such as CPT 81002, 81025, 82270, 82272, 82962, 83026, 84830, 85013, and 85651, subject to current CMS updates).

Commercial Insurance Rules

Commercial payer policies vary.

Some commercial insurers:

Require Modifier QW.
Require only the CLIA number.
Accept claims without QW.
Follow Medicare CLIA policies.

Always verify payer-specific laboratory billing guidelines.

Documentation Requirements

Documentation should include:

Physician or qualified practitioner order (when required).
Test performed.
Test result.
Date and time performed.
Manufacturer-approved testing method.
Appropriate CLIA certificate information.
Medical necessity.
Ordering provider documentation.

Real Billing Examples

Example 1 – Rapid Strep Test

A physician performs an FDA-approved waived rapid strep test.

Billing

CPT 87880-QW
Appropriate diagnosis
CLIA number reported on the claim, if required.

Example 2 – Influenza Test

An urgent care clinic performs a waived influenza test.

Billing

CPT 87804-QW
Appropriate diagnosis

Example 3 – Drug Screening

A physician office performs a waived urine drug screen using an FDA-approved waived device.

Billing

CPT 80305-QW

Example 4 – Pregnancy Test

A urine pregnancy test (CPT 81025) is performed.

Billing

CPT 81025

No Modifier QW is required, because Medicare recognizes this code as inherently waived.

Example 5 – Incorrect Billing

A provider bills:

87880
No QW modifier

The claim may deny if the specific waived test requires Modifier QW.

CMS-1500 Claim Example

Field	Example
CPT	87880
Modifier	QW
Diagnosis Pointer	J02.9
CLIA Number	Enter in the appropriate CMS-1500 field (Item 23) when required by payer instructions
Units	1

Common Denials

Missing Modifier QW.
Missing CLIA number.
Invalid CLIA certificate.
Wrong CPT code.
QW used on a code that does not require it.
Laboratory not certified.
Device not FDA-approved as waived.

Correcting Denials

Verify current CMS QW requirements.
Confirm the laboratory holds the proper CLIA certificate.
Verify the CPT code requires Modifier QW.
Add the CLIA number if missing.
Submit a corrected claim.
Appeal with supporting documentation if appropriate.

Coding Tips

Always verify the current CMS list of waived tests.
Do not assume every laboratory CPT code requires QW.
Keep CLIA certification current.
Verify the test kit is FDA-approved as waived.
Review CMS updates regularly because new waived tests are added throughout the year.

Modifier QW vs CLIA Number

Item	Purpose
Modifier QW	Identifies a CLIA-waived laboratory test (when required)
CLIA Number	Identifies the laboratory’s certification

Modifier QW vs Modifier 90

Modifier	Description
QW	CLIA-waived laboratory testing
90	Reference (outside) laboratory

Modifier QW vs Modifier 91

Modifier	Description
QW	CLIA-waived test
91	Repeat clinical diagnostic laboratory test

Frequently Asked Questions (FAQs)

Q1. What does Modifier QW mean?

Answer: It identifies that the laboratory service is a CLIA-waived test.

Q2. Does every CLIA-waived test require Modifier QW?

Answer: No. CMS identifies certain CPT codes as inherently waived, meaning they do not require QW. Other waived tests do require QW. Always verify the current CMS list.

Q3. Is a CLIA certificate required?

Answer: Yes. Providers performing CLIA-waived testing must hold an appropriate CLIA certificate (or a higher certification level that includes waived testing).

Q4. Can commercial insurance require QW?

Answer: Yes. Many commercial payers follow Medicare guidance, but requirements vary.

Q5. Where is the CLIA number reported on the CMS-1500 claim?

Answer: It is typically reported in Item 23 (Prior Authorization Number field), as directed by Medicare and many commercial payers for laboratory claims.

AR Caller Tips

When following up on QW modifier denials:

Verify the provider’s CLIA certification.
Confirm the CPT code requires Modifier QW.
Check whether the CLIA number was submitted.
Verify the laboratory device is FDA-approved as waived.
Document payer reference numbers and appeal instructions.

Interview Questions

Question 1

What does Modifier QW identify?

Answer: A CLIA-waived laboratory test.

Question 2

Does every waived laboratory CPT code require QW?

Answer: No. Some waived CPT codes are recognized by Medicare without Modifier QW.

Question 3

Why are claims denied without Modifier QW?

Answer: Because some CLIA-waived tests specifically require QW for Medicare to recognize them as waived.

Question 4

What additional information is commonly required on the claim?

Answer: The provider’s CLIA number when required by payer policy.

Practice Scenario

Scenario

A physician office with a valid CLIA Certificate of Waiver performs a rapid influenza test using an FDA-cleared waived testing device. The CPT code for that device requires Modifier QW.

Question

How should the claim be billed?

Answer

Report:

87804-QW
Appropriate diagnosis code
CLIA number on the claim, if required

This identifies the service as a CLIA-waived laboratory test performed by an appropriately certified provider.

Related Medicare Special Modifiers

90 – Reference (Outside) Laboratory
91 – Repeat Clinical Diagnostic Laboratory Test
QP – Documentation Is on File Showing That the Laboratory Test Was Performed Individually or Ordered as a Profile or Panel
TS – Follow-up Service
GA – Waiver of Liability Statement Issued

Common Billing Mistakes

Forgetting Modifier QW when required.
Appending QW to CPT codes that do not require it.
Missing CLIA certification.
Reporting the wrong CPT code.
Using non-waived testing devices.
Omitting the CLIA number.

Key Takeaways

Modifier QW identifies CLIA-waived laboratory tests.
Providers must have the appropriate CLIA certification to perform waived testing.
Some CPT codes require Modifier QW, while others are inherently recognized as waived and do not require it.
Medicare updates the list of waived tests as the FDA approves new devices.
Accurate use of Modifier QW and the CLIA number helps prevent laboratory claim denials.

References

CMS MLN Matters – New Waived Tests (Updated 2025).
CMS Medicare Claims Processing Manual – New Waived Tests Updates.
CMS MLN Matters – New Waived Tests (MM12504).
HCPCS Level II Code Book.
CPT® Professional Edition (American Medical Association).

Conclusion

Modifier QW is a critical Medicare modifier used to identify CLIA-waived laboratory testing. Correct use depends on three key factors: the laboratory’s CLIA certification, whether the specific CPT/HCPCS code requires QW, and compliance with current CMS guidance. Because CMS frequently updates the list of FDA-approved waived tests, billers and coders should review CMS publications regularly to ensure accurate claim submission, reduce denials, and maintain regulatory compliance.

Educational Disclaimer

This article was prepared with the assistance of artificial intelligence (AI) for educational and informational purposes. It is based on publicly available CMS guidance, CLIA regulations, HCPCS Level II guidance, and general medical billing principles. It is not an official publication of CMS, the FDA, or the American Medical Association (AMA). Always consult the latest CMS Medicare Claims Processing Manual, CLIA regulations, HCPCS Level II Code Book, CPT® Professional Edition, FDA CLIA Waived Test Database, and payer-specific laboratory billing policies before coding, billing, or submitting claims.