Pediatric Coding Alert

Modifiers:

Know These Modifier QW Dos and Don’ts

Published on Mon Jul 08, 2024

Hint: Check the CLIA list every time you’re submitting a new lab test.

Some coding modifiers have become fairly self-explanatory over time, thanks to simple descriptors such as the one for modifier 50 (Bilateral procedure). Others, however, can be fraught with confusion — and for many coders, modifier QW (CLIA waived test) is right up there among the most puzzling.

To get a handle on the best ways to ensure you’re reporting modifier QW properly, check out two times you need to use it, and two times you should leave it off your claim.

1. Do Use QW When Your Lab Is CLIA-Waived

If you’re reporting a code for a test performed in a Clinical Laboratory Improvement Amendments- (CLIA-) waived lab, you must append modifier QW to your CPT^® code.

Here’s what that means: To perform waived tests, a lab doesn’t need to meet the requirements mandated for more complicated tests, but the lab does need a CLIA certificate of waiver and must follow manufacturer instructions for how to perform the test. Go to the CMS website to obtain a waiver.

In some states, labs are exempt from having to apply for a CLIA waiver certificate. You can check whether your state requires it on the CMS website.

2. Do Use QW When You Perform a Service on the Waived Test List

Once you confirm that your lab is operating under a CLIA waiver, you should then evaluate which specific tests you’re actually performing. Not every lab test in the CPT^® code book is billable by CLIA-waived labs.

For example, CLIA-waived labs cannot perform tests that require microscopy, but they can perform many simpler tests, such as the COVID-19 test described by 87635 (Infectious agent detection by nucleic acid (DNA or RNA); severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (coronavirus disease [COVID-19]), amplified probe technique). If you bill this code, you’ll always append modifier QW to it.

Remember: You should never assume that a particular service is on the CLIA-waived list — always check first. The Centers for Medicare & Medicaid Services (CMS) updates the list of CLIA-waived test codes each quarter, and the most recent one was issued in December 2023.

In addition, Look to the full list of allowable CLIA-waived tests on the U.S. Food & Drug Administration.

Keep in mind that some payers and states maintain their own lists of CLIA-waived tests, so always check with your insurer and state listing to confirm which tests are on their list.

3. Don’t Use QW as a Blanket Modifier on Lab Tests

Some providers may feel like they’re protecting themselves by using modifier QW on every lab test they perform, but this won’t allow you to prevent denials. Quite the opposite, in fact.

“Some CLIA waived tests do not require the QW modifier and if the modifier is appended in error, the service will be rejected from claim processing,” said Part B MAC Novitas Solutions in a Fact Sheet.

This means that if you withhold the QW modifier on tests that require it, you’ll get denials — and if you append modifier QW on codes for tests that don’t require it, you’ll also get denials.

That’s why it’s imperative to have the list of CLIA-waived tests handy and to consult it every time you perform lab testing.

4. Don’t Use QW if Your Lab Has a CLIA Certificate of Compliance

Although modifier QW is essential for labs with a certificate of waiver, that’s not the case if you have a certificate of compliance. These are two different certificates, and which one your lab possesses will guide your modifier QW use.

Here’s the difference: The certificate of compliance means that your lab is approved to perform lab tests that are CLIA-waived, moderate-complexity, and/or high-complexity, and that your lab has passed inspection.

Labs that have a certificate of waiver are approved to perform only CLIA-waived tests. As such, these labs must append modifier QW to attest that the test they’re billing is indeed CLIA-waived.

Additional Tips for Using Modifier QW

In addition to following the do’s and don’ts above, you should consider heeding these additional strategies to ensure you’re using modifier QW correctly:

Modifier QW won’t change the actual reimbursement you’ll receive for lab tests, but it will help prevent denials.

Not all payers require modifier QW. Be sure to verify whether any non-Medicare payers want the modifier on applicable claims.

Most insurers require you to get a CLIA certification for every location where you perform lab testing. Getting one certification to cover multiple lab locations is not acceptable.

If a new test is added to the list of CLIA-waived tests, you’ll need to start appending modifier QW to that code going forward. However, your Medicare contractor won’t start denying claims retroactively. In other words, if a code becomes CLIA-waived effective July 1, you won’t face denials for dates of service on June 20 that are missing QW. However, after July 1, you must use the modifier.

If you have any questions about using modifier QW, contact your payer and get its modifier regulations in writing.