No. Q5101 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 Q5101?

CMS's ASP crosswalk for October 1, 2026 through December 31, 2026 lists 4 NDCs under Q5101, for Zarxio. The table on this page shows each one with its billing units per package.

What is the Medicare payment limit for Q5101?

$0.338 per 1 mcg, 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 Q5101?

One unit of Q5101 is 1 microgram, as stated in the code's descriptor. Units to report = dose given ÷ 1 microgram.

Q5101 HCPCS Code: Zarxio (filgrastim-sndz) — Billing Units

In short

Q5101 is the HCPCS Level II code for injection, filgrastim-sndz, biosimilar, (zarxio), 1 microgram. CMS assigns NDCs for Zarxio to it. One billing unit is 1 microgram. The Medicare Part B payment limit is $0.338 per unit (October 1, 2026 through December 31, 2026).

Code

CMS HCPCS file

HCPCS codeQ5101

Billing unit1 microgram

Descriptor: Injection, filgrastim-sndz, biosimilar, (zarxio), 1 microgram
Short descriptor: Injection, zarxio
Code set: HCPCS Level II, maintained by CMS
Effective: Jan 1, 2024

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$0.338

Per1 mcg

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: 8% of reference add-on applied. 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 Q5101

CMS’s ASP NDC–HCPCS crosswalk (effective October 1, 2026 through December 31, 2026) assigns 4 NDCs to Q5101 for Zarxio. Billing units per package are CMS’s figures for this code’s unit.

NDCs assigned to Q5101 in the CMS ASP crosswalk
Drug	NDC (11-digit)	Labeler	Package	Billing units per package
Zarxio	61314-0318-01	Sandoz Inc.	0.5	300
Zarxio	61314-0318-10	Sandoz Inc.	10 × 0.5	3,000
Zarxio	61314-0326-01	Sandoz Inc.	0.8	480
Zarxio	61314-0326-10	Sandoz Inc.	10 × 0.8	4,800

Q5101: common questions

Is Q5101 a CPT code?: No. Q5101 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 Q5101?: CMS's ASP crosswalk for October 1, 2026 through December 31, 2026 lists 4 NDCs under Q5101, for Zarxio. The table on this page shows each one with its billing units per package.
What is the Medicare payment limit for Q5101?: $0.338 per 1 mcg, 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 Q5101?: One unit of Q5101 is 1 microgram, as stated in the code's descriptor. Units to report = dose given ÷ 1 microgram. J-code billing units.

Q5101 — Injection, filgrastim-sndz, biosimilar, (zarxio), 1 microgram