QW Modifier: Billing CLIA-Waived Tests
QW is the two-character modifier that tells Medicare a lab test ran on a CLIA-waived test system. For a site holding a certificate of waiver or a PPM certificate, it decides whether a strep test or an A1c is paid or denied. Here is what it signals, which codes carry it, where CMS posts new waived codes each quarter, and what the denial looks like. Every rule here was read from CMS and FDA on 23 October 2026.
Does this claim line need QW?
Medicare checks every lab line against the CLIA certificate behind the CLIA number on the claim. Find your certificate in the left column, then the kind of test you ran.
- passes the CLIA edit as shown
- passes; confirm the modifier with your MAC
- fails the CLIA edit
| Certificate on the claim | Waived test, code listed with QW | Moderate or high complexity test |
|---|---|---|
| Certificate of waiver type 2 | Passes only with QW | Fails the edit |
| Certificate for PPM procedures type 4 | Passes only with QW | Fails, PPM procedures aside |
| Compliance, accreditation or registration types 1, 3, 9 | Passes; ask your MAC about QW | Passes |
From CMS's October 2026 update (MM14569) and the Claims Processing Manual, Ch. 16 §§ 70.8–70.9. Some waived tests have their own codes and are recognized without QW. The edit is only the CLIA check: medical necessity and payer rules still apply to every line.
What QW tells Medicare
The Claims Processing Manual puts it in four words: "QW denotes a CLIA waiver test" (Ch. 16). Medicare edits "all claims submitted for laboratory tests subject to CLIA" at the CLIA certificate level (§ 70.9). The claim carries your 10-character CLIA number, in the 837P REF segment with qualifier X4 or in item 23 of a paper CMS-1500 (§ 70.10), and the edit compares each line with the certificate behind that number.
A lab with a certificate of waiver (type 2) or a PPM certificate (type 4) is not certified for moderate or high complexity work. CMS's October 2026 update says such a lab will not be paid for tests subject to CLIA edits "unless you bill the appropriate HCPCS code with a QW modifier" (MM14569). QW is the line's statement that the test was run on a waived system.
QW does not change the price. In CMS's 2026 quarter 4 fee file, every one of the 126 lines that carries QW pays exactly what the same code pays without it. The modifier is about permission, not payment amount.
The device decides, not the code
FDA categorizes test systems, so one code can be run on a waived analyzer in one office and a moderate complexity analyzer in another. A test system FDA has not yet categorized defaults to high complexity (FDA, CLIA Categorizations). Put QW on a line only when the exact test system you ran is waived (what makes a test waived).
Which waived codes need it
The manual again: "some CLIA waived tests have unique HCPCS procedure codes and some must have a QW modifier included with the HCPCS code" (§ 70.8). CMS does not keep one standing list of every code that needs QW. It sends the waived list to the Medicare Administrative Contractors (MACs) "on a quarterly basis via a Recurring Update Notification", so the current answer lives in the latest quarterly update. Check the waived-tests table in CMS's latest quarterly CLFS/CLIA update (October 2026: CR 14569).
The fee file shows the pattern for common office tests. A QW line means CMS recognizes a waived version of that code:
| Code | Test, in plain words | QW line in the file | 2026 rate |
|---|---|---|---|
| 82947 | Blood glucose, quantitative | Yes | $3.93 |
| 83036 | Hemoglobin A1c | Yes | $9.71 |
| 80061 | Lipid panel | Yes | $13.39 |
| 87880 | Rapid strep A antigen, read by eye | Yes | $16.53 |
| 81003 | Urinalysis on an automated reader, no microscopy | Yes | $2.25 |
| 80305 | Drug screen read by eye (cups, dip cards) | Yes | $12.60 |
| 81002 | Urinalysis by dipstick read by hand, no microscopy | No QW line | $3.48 |
| 82962 | Glucose on a handheld meter | No QW line | $3.28 |
CMS fee file 26CLABQ4 (CY 2026, quarter 4), read 2026-10-23. National rates; the QW line pays the same as the plain code.
Two codes in the table, 81002 and 82962, have no QW line at all in the 2026 file. § 70.8 allows for that: some waived tests are recognized by their own code. Before your system adds or strips QW on either, check how your MAC lists them.
Takeaway
How to check CMS's quarterly list
- Look up the exact test system in FDA's CLIA database: manufacturer, model and analyte, with its complexity. Waived is a property of that listing.
- Find the code in the latest quarterly update. October 2026 is CR 14569, announced in MLN Matters MM14569 (released August 24, 2026, effective October 1). The waived-tests table is in the CR 14569 transmittal. Codes marked Y there "must include the QW modifier to be recognized as waived tests".
- Confirm the line in the fee file. CMS posts each quarter's fee file on its CLFS files page; a waived code appears a second time with QW in the modifier column and its own effective date.
- Load it into your billing rules keyed to the certificate type, so a waiver or PPM site gets QW and nobody types it by hand.
Recent quarters show how small and specific the changes are. CR 14273 added 87494QW and 87812QW effective January 1, 2026 (MM14273). CR 14569 lists one new waived code, 0442U with QW, for a fingerstick respiratory infection test, waived from March 24, 2026; the Q4 fee file carries 0442U-QW with that effective date.
Ran a newly waived test before the update reached your MAC?
MM14273: "MACs won't search their files to either retract payment or retroactively pay claims. However, MACs will adjust claims if you bring them to their attention." Denied lines from that gap stay denied until you ask.
The denial it prevents
A waived test billed without QW from a waiver or PPM site looks, to the edit, like a test outside the certificate. For a physician office lab, Ch. 16 § 70.11 gives contractors the remittance codes for that case:
| What went wrong | Group | Reason code | Remark | Rule |
|---|---|---|---|---|
| Physician office lab billed a test its certificate does not cover | CO | CARC B7 | none; patient notice MSN 14.1 | § 70.11 |
| No CLIA number on the claim | CO or PR | CARC 16 | MA120 | § 70.10.1 |
Two more traps sit in § 70.10: a CLIA number in the wrong format is returned as unprocessable, and so is a claim with more than one CLIA number unless the second belongs to a reference lab. A physician who tests in more than one office lab sends a separate claim for each CLIA number.
The fix is a corrected line, not an argument: confirm the test system is waived, add QW, and resubmit. If a redetermination is needed, it is due "within 120 calendar days from the date a party receives the notice of the initial determination" (§ 405.942(a)), and every claim must be filed no later than "1 calendar year after the date of service" (§ 424.44).
Takeaway
Where QW lives in your billing system
QW logic needs two inputs your software has to hold: the certificate type of each testing site and the current waived-code table. Neither is on a vendor's brochure. Our lab billing software comparison found no vendor documenting QW logic on its public pages, and the XiFin vs TELCOR demo script asks each one who loads the quarterly table. If an outside firm bills for you, put the same question to it (lab billing companies compared).
Not sure which certificate a site holds, or whether its menu has outgrown a waiver? The CLIA certificate finder answers it from the test menu, and how to get a CLIA certificate covers the move to a registration certificate. A blood draw on the same visit is billed on its own code: see CPT 36415.
QW at a glance
- What QW meansa CLIA waiver test
- Who must add itwaiver (type 2) and PPM (type 4) sites
- Where new waived codes appearthe quarterly CR (Oct 2026: CR 14569)
- Rate with QWsame as the plain code
- Office lab, test outside certificateCO, CARC B7
- No CLIA number on the claimCARC 16, RARC MA120