HCPCS code Q4121: Skin substitute, theraSkin per square centimeter2026 Medicare rate & RVUs in California

Medicare pays $139.47–$183.51 for Q4121 in the office in California, from Bakersfield, CA to Santa Clara County, CA. 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.

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.

Where Q4121 pays more and less in California

The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.

29 of 29 payment localities

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.

Payment rules and modifiers for Q4121

The CMS indicators that decide how Q4121 is paid alongside other services.

Q4121 compared with similar codes

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.

Codes related to Q4121

Related codes aren’t interchangeable: bill the code that matches the service performed.

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

Open CMS sourceHow we calculate rates