No. J9356 is a HCPCS Level II code, maintained by CMS, that identifies the drug supplied. CPT codes are five-digit numbers from the AMA that describe services. Giving the drug, for example an injection or infusion, is usually reported with a separate CPT administration code.

What NDCs are billed under J9356?

CMS's ASP crosswalk for October 1, 2026 through December 31, 2026 lists 1 NDC under J9356, for Herceptin Hylecta. The table on this page shows each one with its billing units per package.

What is the Medicare payment limit for J9356?

$58.038 per 10 mg, effective October 1, 2026 through December 31, 2026, from CMS's Part B drug payment limit file. Multiply by the units billed for the allowed amount before deductible and coinsurance. It is not a coverage decision.

What is one billing unit of J9356?

One unit of J9356 is 10 mg and hyaluronidase-oysk, as stated in the code's descriptor. Units to report = dose given ÷ 10 mg and hyaluronidase-oysk.

J9356 J-Code: Herceptin Hylecta (trastuzumab)

In short

J9356 is the HCPCS Level II code for injection, trastuzumab, 10 mg and hyaluronidase-oysk. CMS assigns NDCs for Herceptin Hylecta to it. One billing unit is 10 mg and hyaluronidase-oysk. The Medicare Part B payment limit is $58.038 per unit (October 1, 2026 through December 31, 2026).

Code

CMS HCPCS file

HCPCS codeJ9356

Billing unit10 mg and hyaluronidase-oysk

Descriptor: Injection, trastuzumab, 10 mg and hyaluronidase-oysk
Short descriptor: Inj. herceptin hylecta, 10mg
Code set: HCPCS Level II, maintained by CMS
Effective: Jul 1, 2019

The billing unit is read from the descriptor. Confirm it against the CMS file before billing.

Medicare Part B payment limit

CMS ASP file

Payment limit per unit$58.038

Per10 mg

Coinsurance20%

Effective October 1, 2026 through December 31, 2026. Payment allowance limits subject to the ASP methodology are based on 2Q26 ASP data. A payment limit is not a coverage decision; the Medicare contractor decides coverage. CMS ASP pricing files

Units and claim line

Units = dose given ÷ 10 mg and hyaluronidase-oysk. For example, 1000 mg is 100 units. Enter the dose to get the units and the NDC line for the CMS-1500 and the 837P.

Dose given (mg)

HCPCS units (1 unit = 10 mg)

Modifier

NDC (11-digit)

NDC unit qualifier

NDC quantity

Enter the dose given to build the claim line.

NDCs billed under J9356

CMS’s ASP NDC–HCPCS crosswalk (effective October 1, 2026 through December 31, 2026) assigns 1 NDC to J9356 for Herceptin Hylecta. Billing units per package are CMS’s figures for this code’s unit.

NDCs assigned to J9356 in the CMS ASP crosswalk
Drug	NDC (11-digit)	Labeler	Package	Billing units per package
Herceptin Hylecta	50242-0077-01	Genentech, Inc.	6	60

J9356: common questions

Is J9356 a CPT code?: No. J9356 is a HCPCS Level II code, maintained by CMS, that identifies the drug supplied. CPT codes are five-digit numbers from the AMA that describe services. Giving the drug, for example an injection or infusion, is usually reported with a separate CPT administration code. CPT codes for drug administration.
What NDCs are billed under J9356?: CMS's ASP crosswalk for October 1, 2026 through December 31, 2026 lists 1 NDC under J9356, for Herceptin Hylecta. The table on this page shows each one with its billing units per package.
What is the Medicare payment limit for J9356?: $58.038 per 10 mg, effective October 1, 2026 through December 31, 2026, from CMS's Part B drug payment limit file. Multiply by the units billed for the allowed amount before deductible and coinsurance. It is not a coverage decision.
What is one billing unit of J9356?: One unit of J9356 is 10 mg and hyaluronidase-oysk, as stated in the code's descriptor. Units to report = dose given ÷ 10 mg and hyaluronidase-oysk. J-code billing units.

J9356 — Injection, trastuzumab, 10 mg and hyaluronidase-oysk