No. J1566 is a HCPCS Level II code, maintained by CMS, that identifies a drug with no specific code of its own. 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 NDC goes with J1566?

None is fixed. J1566 is used for drugs that have no specific HCPCS code, so the claim carries the NDC of the drug actually given and its quantity, and payers usually also ask for the drug name and dose.

What is the Medicare payment limit for J1566?

$82.756 per 500 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.

J1566 J-Code: Gammagard S/D (immune globulin)

In short

J1566 is the HCPCS Level II code for injection, immune globulin, intravenous, lyophilized (e.g., powder), not otherwise specified, 500 mg: drugs with no specific code of their own. It has no fixed drug or unit, so the claim carries the NDC of the drug given and its quantity.

Code

CMS HCPCS file

HCPCS codeJ1566

Billing unit500 mg

Descriptor: Injection, immune globulin, intravenous, lyophilized (e.g., powder), not otherwise specified, 500 mg
Short descriptor: Immune globulin, powder
Code set: HCPCS Level II, maintained by CMS
Effective: Jan 1, 2008

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$82.756

Per500 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

Enter the dose to get the units and the NDC line for the CMS-1500 and the 837P.

HCPCS units

Modifier

NDC (11-digit)

NDC unit qualifier

NDC quantity

Enter the units to build the claim line.

NDCs billed under J1566

CMS’s ASP NDC–HCPCS crosswalk (effective October 1, 2026 through December 31, 2026) assigns 2 NDCs to J1566 for Gammagard S/D. Billing units per package are CMS’s figures for this code’s unit.

NDCs assigned to J1566 in the CMS ASP crosswalk
Drug	NDC (11-digit)	Labeler	Package	Billing units per package
Gammagard S/D	00944-2656-03	Takeda Pharmaceuticals America, Inc.	1	10
Gammagard S/D	00944-2658-04	Takeda Pharmaceuticals America, Inc.	1	20

J1566: common questions

Is J1566 a CPT code?: No. J1566 is a HCPCS Level II code, maintained by CMS, that identifies a drug with no specific code of its own. 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 NDC goes with J1566?: None is fixed. J1566 is used for drugs that have no specific HCPCS code, so the claim carries the NDC of the drug actually given and its quantity, and payers usually also ask for the drug name and dose. How to find a J-code.
What is the Medicare payment limit for J1566?: $82.756 per 500 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.

J1566 — Injection, immune globulin, intravenous, lyophilized (e.g., powder), not otherwise specified, 500 mg