In simple words: If a lab test doesn't need the usual strict checks because it's simple, the QW code is added to the bill. This tells Medicare and Medicaid that it was done in a place that's approved for these simpler tests, even if it doesn't have the full certification usually needed.

This modifier is used with codes for individual laboratory tests that have been waived by the FDA from CLIA requirements. All medical laboratories, including physician office laboratories, must have CLIA certification to receive payments from Medicare and Medicaid. The FDA waives some tests from CLIA requirements, and CMS publishes a list of these waived tests quarterly. Providers use this list to determine if a test is eligible for the QW modifier.

Example 1: A physician's office laboratory performs a waived test, such as a urine dipstick test, and appends QW to the appropriate CPT code., A small clinic with a CLIA waiver performs a glucose test, a waived test, and uses the QW modifier to indicate the test's waived status., A healthcare provider performs a fecal occult blood test, another example of a waived test, and adds the QW modifier while billing to signify its compliance with CLIA waiver policies.

Documentation should support the medical necessity of the waived test and confirm the test's inclusion in the CMS list of CLIA-waived tests.