No. J0644 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 J0644?

CMS's ASP crosswalk for October 1, 2026 through December 31, 2026 lists 3 NDCs under J0644, for Vykoura. The table on this page shows each one with its billing units per package.

What is the Medicare payment limit for J0644?

$2.625 per 1 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 J0644?

One unit of J0644 is 1 mg, as stated in the code's descriptor. Units to report = dose given ÷ 1 mg.

J0644 J-Code: Vykoura (leucovorin calcium) — Billing Units

In short

J0644 is the HCPCS Level II code for injection, leucovorin calcium (avyxa), 1 mg. CMS assigns NDCs for Vykoura to it. One billing unit is 1 mg. The Medicare Part B payment limit is $2.625 per unit (October 1, 2026 through December 31, 2026).

Code

CMS HCPCS file

HCPCS codeJ0644

Billing unit1 mg

Descriptor: Injection, leucovorin calcium (avyxa), 1 mg
Short descriptor: Inj, leucovorin cal (avyxa)
Code set: HCPCS Level II, maintained by CMS
Effective: Oct 1, 2026

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$2.625

Per1 mg

Coinsurance20%

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

Units and claim line

Units = dose given ÷ 1 mg. For example, 100 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 = 1 mg)

Modifier

NDC (11-digit)

NDC unit qualifier

NDC quantity

Enter the dose given to build the claim line.

NDCs billed under J0644

CMS’s ASP NDC–HCPCS crosswalk (effective October 1, 2026 through December 31, 2026) assigns 3 NDCs to J0644 for Vykoura. Billing units per package are CMS’s figures for this code’s unit.

NDCs assigned to J0644 in the CMS ASP crosswalk
Drug	NDC (11-digit)	Labeler	Package	Billing units per package
Vykoura	83831-0147-05	Avyxa Pharma, LLC	5	50
Vykoura	83831-0148-35	Avyxa Pharma, LLC	35	350
Vykoura	83831-0149-50	Avyxa Pharma, LLC	50	500

J0644: common questions

Is J0644 a CPT code?: No. J0644 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 J0644?: CMS's ASP crosswalk for October 1, 2026 through December 31, 2026 lists 3 NDCs under J0644, for Vykoura. The table on this page shows each one with its billing units per package.
What is the Medicare payment limit for J0644?: $2.625 per 1 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 J0644?: One unit of J0644 is 1 mg, as stated in the code's descriptor. Units to report = dose given ÷ 1 mg. J-code billing units.

J0644 — Injection, leucovorin calcium (avyxa), 1 mg