CareCost Vials
2 × 400 mg
1 billing unit = 10 mg
800 mg dose → 80 billing units
J0490 · belimumab
120 mg and 400 mg single-dose vials · JW/JZ waste rules may apply
Calculate this patient's units ↓Typical Benlysta dose: 10 mg/kg
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Patient owes, 800 mg
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37 payer price files · Commercial + Medicare · Copay and foundation status · Deductible, coinsurance and out-of-pocket math
Benlysta J0490 is billed in units of 10 mg: weight (kg) × dose (mg/kg) = dose in mg ÷ 10 mg/unit = billing units. Example, the label's 10 mg/kg dose: 80 kg × 10 mg/kg = 800 mg ÷ 10 = 80 billing units.
Benlysta ships in two vial sizes, 120 mg and 400 mg, and the mg drawn can exceed the mg administered. This page applies the fewest-vials rule: pick the combination that uses the smallest number of vials, even if that leaves some drug undrawn. Report any leftover as JW; use JZ only when nothing was discarded. A 700 mg dose still draws two 400 mg vials rather than one 400 mg plus three 120 mg vials, because two vials is fewer — real money, as the table below shows.
Medicare pays $58.333 per billing unit for J0490, effective for claims in Q4 2026:
$4,666.64 for the 80-unit example above, plus $67.14 for the 96365 administration line.
One 10 mg/kg schedule covers both indications and every age from 5 years, so weight is what moves the units below; the fewest-vials rule finds each patient's draw from the two available vial sizes.
| Patient | Weight | Dose | Units | Vials drawn | Modifier |
|---|---|---|---|---|---|
| Adult, default | 80 kg | 800 mg | 80 | 2 × 400 mg | JZ |
| Lower-weight adult | 70 kg | 700 mg | 70 | 2 × 400 mg (100 mg discarded) | JW |
| Higher-weight adult | 100 kg | 1,000 mg | 100 | 3 × 400 mg (200 mg discarded) | JW |
| Child, 5 years and older | 30 kg | 300 mg | 30 | 1 × 400 mg (100 mg discarded) | JW |
The label sets no maximum dose, so the calculator multiplies 10 mg/kg through at any weight; the J0490 MUE is 160 units (1,600 mg) a day, well above a single infusion at these weights. Only the 80 kg row draws two full vials with nothing left over. Every other row opens the fewest vials the fewest-vials rule allows rather than the least amount of waste — a 70 kg dose still draws two 400 mg vials instead of a 400 mg plus three 120 mg combination, and reports the difference on a JW line, as the next section works through.
JZ — no discarded drug from a single-dose container. JW — discarded drug from a single-dose container, reported on its own claim line.
J0490 × 80 JZ · 96365 × 1.
J0490 × 70 · J0490 × 10 JW · 96365 × 1.
96365 covers the initial hour of a therapeutic, prophylactic or diagnostic infusion. Every IV Benlysta dose is reconstituted, diluted and administered as a single 1-hour drip infusion, never a bolus or push, so the claim reports 96365 × 1 alone. 96366 (each additional hour) applies only once the infusion passes 90 minutes total, which a 1-hour drip does not reach unless it is slowed or held for a reaction.
Premedication given before the infusion is not itself infusion time. If a practice slows or holds the drip for a reaction, only the drip minutes count toward 96365/96366; the label sets no maximum dose, so the units line has no cap of its own, but the J0490 MUE is 160 units (1,600 mg) a day.
The schedule is fixed for both indications: 10 mg/kg IV at weeks 0, 2 and 4, then every 4 weeks, ; the label sets no stopping point. The subcutaneous 200 mg autoinjector and prefilled syringe run on a separate weekly schedule and bill to the pharmacy benefit, never this administration code or J0490.
Benlysta IV ships as a lyophilized powder in two single-dose vials: 120 mg/5 mL (NDC 49401-101-01) and 400 mg/20 mL (NDC 49401-102-01). Each vial is reconstituted with sterile water to an 80 mg/mL concentration, then diluted into a 250 mL bag of 0.9% sodium chloride, 0.45% sodium chloride or Lactated Ringer's (a 100 mL bag may be used for a patient at or under 40 kg) before the 1-hour infusion.
A subcutaneous 200 mg/mL product is also on the label, as a prefilled autoinjector (NDC 49401-088-01) or prefilled syringe (NDC 49401-088-42), dosed weekly — a pharmacy-benefit product, not buy-and-bill, and never a J0490 claim. See the FDA Benlysta label (BLA125370) for the full reconstitution and administration instructions.
J0490 is the HCPCS code for reference Benlysta (belimumab) administered intravenously. No belimumab biosimilar exists; the 200 mg subcutaneous autoinjector and prefilled syringe are the same molecule, billed to the pharmacy benefit, never a J0490 claim. The one priced IV alternative in this class is Saphnelo (J0491, anifrolumab-fnia, AstraZeneca), a fixed 300 mg dose for SLE only, priced separately from Benlysta's mg/kg rate. See the HCPCS hub for coding across the full family. The Medicare rate for every quarter is on the cost page →
80 billing units at the label's 10 mg/kg dose. Benlysta J0490 bills 1 unit per 10 mg, so 80 kg × 10 mg/kg = 800 mg ÷ 10 = 80 units, drawn from two 400 mg vials with nothing discarded.
Two 400 mg vials, drawing exactly 800 mg with nothing left over, billed JZ. A lower weight, such as 700 mg for a 70 kg patient, still draws two 400 mg vials under the fewest-vials rule and has to report the extra 100 mg on its own JW line: $583.33 of drug at the Q4 2026 rate of $58.333 per unit.
Either, depending on the draw. A dose that lands exactly on full vials, such as 800 mg from two 400 mg vials, bills JZ. A dose that leaves drug in an opened vial, such as the 700 mg draw above, bills the leftover on a JW line.
96365 alone. 96365 covers the initial hour of a therapeutic, prophylactic or diagnostic infusion, and Benlysta's label-directed 1-hour drip infusion fits entirely inside it. 96366 (each additional hour) only applies once the infusion runs past 90 minutes total, which a 1-hour drip does not do unless it is slowed or held for a reaction; time spent on premedication is not infusion time.
At a single rate for both indications: 10 mg/kg IV at weeks 0, 2 and 4, then every 4 weeks, for active systemic lupus erythematosus or active lupus nephritis on standard therapy, from 5 years of age. The label sets no maximum dose, so the calculator multiplies the ordered mg/kg through at any weight.
$58.333 per billing unit (per 10 mg), effective for claims in Q4 2026: $4,666.64 for the 80-unit example above, plus $67.14 for the 96365 administration line.
Data current: pricing Q4 2026 · payer policies Aug 2026
Sources: CMS ASP pricing files (Q4 2026); FDA-approved prescribing information (BENLYSTA label, revised August 2026, BLA125370); CMS single-dose container JW/JZ policy (effective July 1, 2023); 26 commercial payer medical policies (Clearance corpus); CPT codebook administration-code guidance.
Reviewed September 21, 2026 by Erin Rose, CareCost Estimate founder. Methodology →