QW Modifier Guide: Billing CLIA-Waived Tests
Updated Oct 30, 2026
The QW modifier is a two-character HCPCS modifier added to a lab code to tell Medicare that the test was performed with a CLIA-waived test system. Medicare edits lab claims against each facility's CLIA certificate. A lab that holds only a Certificate of Waiver is paid for waived tests, and QW is how most of those tests are recognized on the claim (CMS transmittal R12415CP).
What "waived" means under CLIA
Under 42 CFR 493.15, waived tests are simple tests with a low risk of an incorrect result. The FDA categorizes test systems by complexity and publishes those decisions in the FDA CLIA database. Waived status applies to a specific manufacturer's test system, not to a CPT code in general. That is why the same code can be waived for one kit and moderate complexity for another.
| CLIA certificate type | Tests the lab may perform | QW relevance |
|---|---|---|
| Certificate of Waiver | Waived tests only | QW is needed on most claims |
| Certificate for Provider-Performed Microscopy (PPM) | Waived tests plus specified microscopy | QW on the waived tests |
| Certificate of Compliance / Accreditation | Waived, moderate-, and high-complexity tests | Follow MAC/payer guidance for waived codes |
Source: CMS CLIA program; 42 CFR Part 493, Subparts A–C.
The nine codes that do not need QW
CMS's waived-test change requests say these HCPCS codes are recognized as waived without a QW modifier (R12415CP):
| Code | Test (paraphrased) | CY 2026 Q4 CLFS amount |
|---|---|---|
| 81002 | Non-automated urine dipstick or tablet, without microscopy | $3.48 |
| 81025 | Urine pregnancy test by visual color comparison | $8.61 |
| 82270 | Fecal occult blood, screening | $4.38 |
| 82272 | Fecal occult blood, other sources | $4.23 |
| 82962 | Blood glucose by a home-use monitoring device | $3.28 |
| 83026 | Hemoglobin by copper sulfate method | $4.01 |
| 84830 | Ovulation test by visual color comparison | $12.70 |
| 85013 | Spun microhematocrit | $7.00 |
| 85651 | Non-automated sedimentation rate | $4.27 |
Amounts are from the CMS CY 2026 Q4 CLFS file (26CLABQ4).
Common waived tests that do carry QW
In the CY 2026 Q4 CLFS file, 126 rows carry the QW modifier. Here are some common examples, each at the same amount as its non-QW row:
| Code + modifier | Test (paraphrased) | CY 2026 Q4 CLFS amount |
|---|---|---|
| 80305-QW | Presumptive drug screen read by direct optical observation | $12.60 |
| 81003-QW | Automated urinalysis without microscopy | $2.25 |
| 82947-QW | Quantitative blood glucose | $3.93 |
| 83036-QW | Hemoglobin A1c | $9.71 |
| 85610-QW | Prothrombin time (PT/INR) | $4.29 |
| 87804-QW | Influenza antigen immunoassay, direct optical observation | $16.55 |
| 87880-QW | Strep A antigen, direct optical observation | $16.53 |
| 87635-QW | SARS-CoV-2 nucleic-acid amplified detection | $51.31 |
How to confirm a test needs QW
| Step | Action |
|---|---|
| 1 | Find the exact kit or analyzer (manufacturer and model) in the FDA CLIA database and confirm "Waived" complexity. |
| 2 | Check the CMS waived-test list for the code and its QW effective date (CMS publishes these lists in change requests such as R12415CP). |
| 3 | If the code isn't one of the nine exempt codes, add QW. |
| 4 | Make sure the CLIA number on the claim is the certificate that covers that site. |
| 5 | Follow the manufacturer's instructions exactly. If you modify a waived test, it is no longer waived (42 CFR 493.15). |
Compliance still applies to waived testing
A waived test isn't exempt from CLIA. Labs with a Certificate of Waiver have to follow manufacturer instructions, and they remain subject to CMS inspection (42 CFR 493.15, 493.35–493.39). myLabCompliance.io helps waived and moderate-complexity sites track kit lots, QC runs, personnel training, and certificate details, so billing and the bench stay aligned.
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FAQs
What does the QW modifier stand for?
CMS defines QW as the modifier for a CLIA-waived test. It tells the claims system that the test was performed with a waived test system.
Does every waived test need QW?
No. CMS exempts nine codes: 81002, 81025, 82270, 82272, 82962, 83026, 84830, 85013, and 85651.
Does QW change the payment amount?
In the CY 2026 Q4 CLFS file, the QW rows carry the same amount as the matching non-QW rows for the codes shown above.
How do I know if my specific kit is waived?
Search the manufacturer and test name in the FDA CLIA database. Waiver applies to that test system, not to every product billed under the code.
Can a lab with a Certificate of Compliance use QW?
The modifier describes the test system, not the certificate. Higher-level certificates cover waived testing, but whether a payer expects QW from those labs depends on its billing policy, so check your Medicare contractor's (MAC's) guidance and payer manuals.
What happens if QW is missing?
A Certificate of Waiver lab's claim can be denied by the CLIA edit, because the code otherwise appears as non-waived.
Do commercial payers require QW?
Policies vary. Many follow Medicare conventions, so check each payer's billing policy.
Where does CMS announce new waived tests?
In quarterly "New Waived Tests" change requests and MLN articles on cms.gov, such as R12415CP.
Sources
- CMS, New Waived Tests transmittal R12415CP: https://www.cms.gov/files/document/r12415cp.pdf
- CMS, CLIA program: https://www.cms.gov/medicare/quality/clinical-laboratory-improvement-amendments
- FDA, CLIA database: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfClia/search.cfm
- eCFR, 42 CFR Part 493: https://www.ecfr.gov/current/title-42/chapter-IV/subchapter-G/part-493
- CMS, CLFS Files (26CLABQ4): https://www.cms.gov/medicare/payment/fee-schedules/clinical-laboratory-fee-schedule-clfs/files