HCPCS code Q4121: Skin substitute, theraSkin per square centimeter2026 Medicare rate & RVUs in Guam
Report Q4121 for TheraSkin human skin allograft used to cover a wound, with units based on square centimeters and an application procedure billed with it.
Medicare pays $144.69 for Q4121 in the office in Guam (Hawaii, Guam, HI). 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.
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What Q4121 covers
Q4121 reports TheraSkin, a human skin allograft supplied for coverage of a wound bed, commonly in care of chronic diabetic foot and venous leg ulcers. It represents the graft material, not the clinician’s wound preparation or application work. Physicians, podiatrists, and other qualified practitioners may use it in outpatient wound clinics, offices, or hospital outpatient departments when a skin substitute is selected as part of wound care. The product is measured per square centimeter, so the product record and wound documentation should support the quantity reported.
Report Q4121 only with the applicable primary skin-substitute application procedure. CMS treats it as an add-on, with payment within that procedure’s global period. CMS assigns no work RVUs and 3.81 practice-expense RVUs in both office and facility settings. Q4121 is technical-component-only; a separate code covers interpretation. Documentation should identify TheraSkin, the wound location and dimensions, the quantity applied, and the associated application procedure so the product units and procedural service can be reconciled.
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.
Q4121 in Hawaii, Guam, HI
| Payment locality | Office | Facility |
|---|---|---|
| Hawaii, Guam, HI | $144.69 | Unavailable |
How the Q4121 rate is calculated
Each of Q4121’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 · Q4121
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 Q4121
The CMS indicators that decide how Q4121 is paid alongside other services.
CMS payment indicators · Q4121
Skin substitute, theraSkin per square centimeter
| 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. |
Q4121 compared with similar codes
Compare codes · National
4 codes, side by side
How to choose
- Q4122Wound matrixDermACELL AWM, per sq cm
- Q4122 identifies Dermacell AWM, not TheraSkin. Select the product code that matches the material applied.
- Q4124Wound matrixOasis tri-layer product
- Q4124 represents Oasis tri-layer wound matrix. It is not interchangeable on the claim with TheraSkin; code the product actually used.
- Q4132Wound matrixGrafix Core or GrafixPL Core
- Q4132 identifies Grafix Core products. Q4121 is specific to TheraSkin, so the product record determines which code applies.
Q4121 billing questions
What distinguishes Q4121 from another skin substitute product code?
Q4121 identifies TheraSkin specifically. Report the product code matching the graft material used, rather than choosing among products based only on wound type.
Does Q4121 include the wound application procedure?
No. Q4121 represents the TheraSkin product and is reported with the applicable primary skin-substitute application procedure.
How should units be determined?
Q4121 is measured per square centimeter. The product record and wound documentation should support the quantity reported.
How does the add-on status affect payment?
CMS requires Q4121 to be billed with a primary procedure and places its payment within that procedure’s global period.
Does Q4121 include interpretation?
CMS classifies Q4121 as technical-component-only; a separate code covers interpretation.
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
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