HCPCS Q4128: Skin matrixMedicare rate & RVUs in Washington
Reports FlexHD or AlloPatch HD biologic matrix by square centimeter when supplied for a skin-substitute application procedure.
Medicare pays $134.00–$156.14 for Q4128 in the office in Washington, from Rest Of Washington to Seattle (King Cnty). Which amount applies depends on the service address.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
On this page 9 sections
What Q4128 covers
Q4128 identifies FlexHD or AlloPatch HD, human-derived biologic matrices used as skin substitutes to cover a wound or support tissue repair. The product may be supplied for wound-care or surgical treatment, with the clinician selecting and applying it to the prepared site. The code represents the named product, not the work of preparing the wound or applying the matrix.
Report Q4128 with the primary procedure for the skin-substitute application, not as a stand-alone service. Units are based on the documented square centimeters of product reported; the record should identify the product, wound site, and amount used. CMS treats this as an add-on code, so payment falls within the primary procedure's global period. CMS classifies it as technical-component-only; a separate code covers interpretation.
This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.
Where Q4128 pays more and less in Washington
| Payment locality | Office | Facility |
|---|---|---|
| Rest Of Washington | $134.00 | Unavailable |
| Seattle (King Cnty) | $156.14 | Unavailable |
How the Q4128 rate is calculated
Each of Q4128’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.
How the rate is built · Q4128
RVUs × geographic indexes × conversion factor
Work0.00
0.00 RVUs× 1.000 GPCI
Practice expense3.81
3.81 RVUs× 1.000 GPCI
Malpractice0.00
0.00 RVUs× 1.000 GPCI
Adjusted RVUs
3.8100
Conversion factor
$33.4009
Medicare rate
$127.26
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for Q4128
The CMS indicators that decide how Q4128 is paid alongside other services.
CMS payment indicators · Q4128
Skin matrix
| Rule | CMS value | What it means |
|---|---|---|
| Global period | ZZZ | Add-on code: falls within the primary procedure’s global period. |
| Multiple procedures | 0 | No multiple-procedure reduction. |
| Bilateral (modifier 50) | 0 | The 150% bilateral adjustment doesn’t apply. |
| Assistant at surgery (80/81/82/AS) | 0 | Not paid without supporting documentation. |
| Co-surgeons (62) | 0 | Not permitted. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 3 | Technical component only. |
Q4128 compared with similar codes
Compare codes · National
4 codes, side by side
How to choose
- 15271Skin substitute graft
- 15271 reports the application procedure for a qualifying wound at its specified anatomic sites; Q4128 identifies the FlexHD or AlloPatch HD product used with a primary application procedure.
- Q4121Skin substitute
- Q4121 identifies TheraSkin. Choose the product code that matches the specific skin substitute supplied; it is not interchangeable with Q4128.
- Q4122Wound matrix
- Q4122 identifies DermACELL AWM. Q4128 is specific to FlexHD or AlloPatch HD, even when the products serve a similar treatment purpose.
Q4128 billing questions
Is Q4128 the application procedure?
No. Q4128 identifies the FlexHD or AlloPatch HD product. Report the applicable skin-substitute application procedure separately as the primary service.
Can Q4128 be billed by itself?
No. CMS identifies it as an add-on code that must be billed with a primary procedure.
How are units determined?
Report the product quantity in square centimeters and document the product and wound site. The code descriptor identifies the unit as one square centimeter.
How does the global-period rule affect payment?
Payment for Q4128 is included within the global period of the primary procedure. It is not paid as a separate stand-alone service outside that procedure.
Does Q4128 include interpretation?
No. CMS classifies Q4128 as technical-component-only, with interpretation covered by a separate code.
Where these rates come from
FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.
CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027
Show the CMS file lines behind this rate
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