This article gives guidance for billing, coding, and other guidelines in relation to local coverage policy Wound Application of Cellular and/or Tissue Based Products (CTPs), Lower Extremities L36690.
Coding Guidance
We are no longer publishing a list of HCPCS codes because it is not necessary to adjudicate the claim.
Do not report non-graft wound dressings or injected skin substitute HCPCS codes with skin substitute graft/cellular and/or tissue-based products (CTP) and HCPCS application codes as this would be considered incorrect coding. Such products are bundled into other standard management procedures if medically necessary and are not separately payable.
Removal of a current graft and/or simple cleansing of the wound and other surgical preparation services are included in the skin substitute graft/CTP and HCPCS application codes. Active wound care management (CPT code 97602. Removal of devitalized tissue from wound(s), non-selective debridement, without anesthesia (e.g., wet-to-moist dressings, enzymatic, abrasion, larval therapy), including topical application(s), wound assessment, and instruction(s) for ongoing care, per session procedures should never be reported in conjunction with skin substitute graft/CTP and HCPCS application codes.
An evaluation and management (E/M) service should only be reported with a skin replacement therapy (application of skin substitute graft/CTP) if the patient required a service that was separate and distinct from the skin replacement service.
Do not report 15271–15278 when a skin substitute is used for anything other than skin replacement.
If reporting a skin substitute product with HCPCS code A4100 (Skin substitute, FDA cleared as a device, not otherwise specified code, Q4431 (Unlisted PMA skin substitute product), Q4432 (Unlisted 501k skin substitute product) or Q4433 (Unlisted 361 HCT/P skin substitute product), the product name, package size purchased, amount applied and amount wasted must be reported in the claim narrative/remarks or the claim will be returned to the provider/rejected.
Part A:
Line Level Remarks for 837I Electronic Claim: 837I 2400 SV202-7
Claim Level Remarks for 837I Electronic Claim: 837I 2300 NTE*ADD
Block 80 for the UB04 claim form
“REMARKS” field for a DDE claim
Part B:
Loop 2400 or SV101-7 for the 5010A1 837P
Box 19 for paper claim
- The name of the product, size, and the amount used must appear in the Documentation Field.
For codes that are not reimbursed at a standardized payment per the CY 2026 Medicare Physician Fee Schedule (PFS) Final Rule if the charge matches the actual invoice cost, note "Actual Invoice Cost" in the Documentation Field. You are not required to submit invoice information with the claim; however, it must be available if requested.
- If you are submitting a charge greater than the actual invoice cost, please include the following information in the Documentation Field, using these abbreviations:
- Des = Description/Name of skin sub/product ()
- QS = Quantity shipped (e.g., QS=3 boxes)
- TA = Total amount charged for quantity shipped (e.g., TA=$437.50)
- UP = Unit Price (e.g., UP = $17.50 per 5X5 cm) (Optional)
- DG = Amount used (e.g., 25 cm)
The appropriate CPT or HCPCS application code must be reported on the same claim as the skin substitute graft/CTP HCPCS code. The claim will be returned to provider or denied if the application code and skin substitute graft/CTP code are not submitted on the same claim. When the skin substitute graft/CTP HCPCS code is denied, the related application code will also be denied.
CGS Administrators expects that where multiple sizes of a specific product are available, the size that best fits the wound with the least amount of wastage will be utilized. Each product material is for a single-use only and is not for use on a multiple patients.
Advance Beneficiary Notice of Non-coverage (ABN) Modifier Guidelines
It is not appropriate to bill Medicare for services that are not covered as if they are covered. When billing for non-covered services, use the appropriate modifier. For Part A and Part B use the use GY (Item or service statutorily excluded, does not meet the definition of any Medicare benefit or, for non-Medicare insurers, is not a contract benefit) or GZ (Item or service expected to be denied as not reasonable and necessary) modifier.
An ABN may be used for services which are likely to be non-covered, whether for medical necessity or for other reasons. Refer to CMS Publication 100-04, Medicare Claims Processing Manual, Chapter 30, for complete instructions.
Effective from April 1, 2010, non-covered services should be billed with modifier –GA, -GX, -GY, or –GZ, as appropriate.
The –GA modifier (“Waiver of Liability Statement Issued as Required by Payer Policy”) should be used when physicians, practitioners, or suppliers want to indicate that they anticipate that Medicare will deny a specific service as not reasonable and necessary and they do have an ABN signed by the beneficiary on file. Modifier GA applies only when services will be denied under reasonable and necessary provisions, sections 1862(a)(1), 1862(a)(9), 1879(e), or 1879(g) of the Social Security Act. Effective April 1, 2010, Part A MAC systems will automatically deny services billed with modifier GA. An ABN, Form CMS-R-131, should be signed by the beneficiary to indicate that he/she accepts responsibility for payment. The -GA modifier may also be used on assigned claims when a patient refuses to sign the ABN and the latter is properly witnessed. For claims submitted to the Part A MAC, occurrence code 32 and the date of the ABN is required.
Modifier GX (“Notice of Liability Issued, Voluntary Under Payer Policy”) should be used when the beneficiary has signed an ABN, and a denial is anticipated based on provisions other than medical necessity, such as statutory exclusions of coverage or technical issues. An ABN is not required for these denials, but if non-covered services are reported with modifier GX, will automatically be denied services.
The –GZ modifier should be used when physicians, practitioners, or suppliers want to indicate that they expect that Medicare will deny an item or service as not reasonable and necessary and they have not had an ABN signed by the beneficiary. If the service is statutorily non-covered, or without a benefit category, submit the appropriate CPT/HCPCS code with the -GY modifier. An ABN is not required for these denials, and the limitation of liability does not apply for beneficiaries. Services with modifier GY will automatically deny.
Documentation Requirements
- All documentation must be maintained in the patient’s medical record and made available to the contractor upon request.
- Every page of the record must be legible and include appropriate patient identification information (e.g., complete name, dates of service(s)). The documentation must include the legible signature of the physician or non-physician practitioner responsible for and providing the care to the patient.
- The submitted medical record must support the use of the selected ICD-10-CM code(s). The submitted CPT/HCPCS code must describe the service performed.
- Medical record documentation must support the medical necessity of the services as directed in this policy.
- The documentation must support that the service was performed and must be included in the patient’s medical record. This information is normally found in the history and physical, office/progress notes, hospital notes, and/or procedure report.
- The medical record must clearly show that the criteria listed under the “Indications and Limitations of Coverage and/or Medical Necessity” sections have been met, as well as, the appropriate diagnosis and response to treatment.
- The documentation must support the need for CTP application and the product used.
- A description of the wound(s) must be documented at baseline (prior to beginning conservative treatment) relative to size, location, stage, duration, and presence of infection, in addition to type of treatment given and response.
- This information must be updated in the medical record throughout treatment.
- Wound description must also be documented pre and post treatment with the skin substitute graft being used.
- If obvious signs of worsening or lack of treatment response is noted, continuing treatment with the skin substitute would not be considered medically reasonable and necessary without documentation of a reasonable rationale for doing so.
- Documentation of smoking history, and that the patient has received counseling on the effects of smoking on surgical outcomes and treatment for smoking cessation (if applicable) as well as outcome of counselling must be in the medical record.
- An operative note must support the procedure (e.g., application of skin substitute graft/CTPs to legs) for the relevant date of service (first application starts the 12 week episode of care) and include the reason for the procedure and a complete description of the procedure including product used (with identifying package label in the chart), and relevant findings.
-
The HCPCS code of the applicable skin substitute graft/CTP and the units billed must be consistent with the medical record regarding wound description and size.
Utilization Guidelines
- A maximum of 10 skin substitute graft/CTP applications per ulcer will be allowed for the episode of skin replacement surgery (defined as 12 weeks from the first application of a skin substitute graft/CTP). Product change within the episode of skin replacement surgery may be appropriate. When more than 1 specific product is used during the 12-week period, it is expected that the total number of applications or treatments will still not exceed 10.
-
Greater than ten (10) applications for the treatment of a single wound within a 12-week period of time, will be considered Not Reasonable and Necessary.
- Separately billed repeated use of the skin substitute after 12 weeks for a single wound or episode is non-covered.
-
The utilization of a CTP non-compliant with medical necessity or designated guidelines for that specific product may necessitate review or non-coverage as not medically necessary.
-
Labeling for most skin substitute grafts include language suggesting multiple applications; however, Medicare does not expect that every ulcer in every patient will require the
maximum number of applications listed on the product label or allowed for reimbursement.
-
Utilization rates that exceed peer norms, identified through data analysis may prompt prepayment or post payment medical review.
Multiple Wounds
- To determine the surface area for application of skin substitute graft code selection for multiple wounds, all areas within the same anatomic grouping should be added. If the surgeon applies skin grafts to wounds on a different anatomic area, they should bill the corresponding application code for legs or feet.
- Do not code modifier -59 on skin substitute, graft application or skin substitute product codes. Skin substitute graft application codes are appropriately coded based upon total surface area of anatomical locations and not by number of ulcers.
- Modifier -50 and modifiers -LT and -RT are not appropriately appended to skin substitute codes. Coding for skin substitute graft application is based upon total surface area of the ulcers; therefore, Modifiers -50, -LT and -RT are not required for proper claim adjudication.
Incident-to-Supply Classification
Effective January 1, 2026, most skin substitutes will no longer be treated as “biologics” and will not be reimbursed under the Average Sales Price (ASP) methodology. Instead, they will be classified as incident-to supplies, receiving a flat-rate payment per sq cm, regardless of brand or product type. This change applies across physician offices and outpatient settings to standardize reimbursement and reduce cost variability.
Wastage Policy
Under the incident-to supply classification:
- Medicare will not provide separate payment for discarded or unused portions of skin substitute products.
- Only the amount actually applied to the patient will be eligible for reimbursement at the per-square-centimeter rate.
- Providers must:
- Accurately calculate the amount needed before opening a product.
- Document the exact amount applied in the medical record.
- Avoid over-ordering or unnecessary product wastage, as this will result in unreimbursed cost.
Providers are encouraged to adopt scheduling practices that minimize single-use or limited-shelf-life product waste and unnecessary resource use. Optimizing scheduling not only improves clinical efficiency but also supports sustainable, cost-effective healthcare delivery.
