Benlysta (belimumab) cost per infusion and what the patient owes

$58.333 per unit (10 mg) is Part B's ASP+6% rate for Q4 2026. Once the $283 Part B deductible is met, the patient owes the remaining 20% coinsurance on the administered drug and the infusion, with no annual out-of-pocket maximum to cap it. A draw that pulls more from a vial than the dose needs is billed on its own discarded-drug line at the same rate. Full explanation: How Medicare Part B drug cost sharing works →

Both indications use the same schedule: 10 mg/kg intravenously at weeks 0, 2 and 4, then every 4 weeks, for patients 5 years and older on standard therapy. There is no separate starting dose, so every infusion bills the same way from the first one. A maintenance year is 13 infusions; the first year, which carries the three loading infusions at weeks 0, 2 and 4, is 15.

The label sets no dose ceiling for Benlysta, so every patient's claim is 10 mg/kg of body weight, and the only variable across patients is how the 120 mg and 400 mg vials fill that dose. A 70 kg patient needs 700 mg: two 400 mg vials under the fewest-vials rule draw 800 mg, so the administered line is 70 units = $4,083.31 and the remaining 100 mg (10 units) is billed on a separate JW line at $583.33. A 100 kg patient needs 1,000 mg: three 400 mg vials draw 1,200 mg, so the administered line is 100 units = $5,833.30 with 200 mg (20 units) discarded on the JW line, $1,166.66.

The J0490 MUE is 160 units a day, 1,600 mg, which is what a 160 kg patient at 10 mg/kg would need: a claim above that line needs its own review, but nothing in the label stops a dose from reaching it. The dose and vial math, including the JW/JZ line, are built the same way at every visit: how the units and the JW/JZ line are built →

For the reference patient (80 kg, 10 mg/kg, 80 units, drug plus the 96365 infusion code), Medicare allows $4,733.78, and the Part B coinsurance on that is $946.76. Plans A, B, C, D, F, G, M and N cover Part B coinsurance in full, so once the deductible is met those patients owe nothing per infusion. Plans K and L do not: Plan K owes $473.37 once the deductible is met and $728.07 before it is; Plan L owes $236.69 and $505.54. Most patients meet the $283 deductible by their first infusion of the year, so the not-met figure applies only once regardless of how often Benlysta is given afterward. See what each Medigap plan (A–N) owes on this claim →

Only the letters that leave this patient a balance are listed. The full A–N grid, the high-deductible variants, Plan N’s office-visit carve-out and the MACRA restriction on Plans C and F are at Medigap Plans A–N.

Payers other than Medicare negotiate their own rate for J0490, not ASP+6%: our corpus holds published rates from 37 of 37 payer files. Aetna’s median is $58.51 per unit against Medicare’s $58.333, putting the 800 mg worked example at $4,680.80 before benefits, close to the $4,666.64 Medicare allows for the same dose. Rates move by state as well as by payer, which is why the estimator above takes one. What the patient owes then depends on their specific benefits. Full explanation: How commercial drug reimbursement works →

No belimumab biosimilar exists. The one priced alternative in the same family is Saphnelo (anifrolumab-fnia, J0491), a different drug class approved only for SLE, not lupus nephritis: it runs $18.46 per 1 mg, and its fixed 300 mg dose, unrelated to patient weight, prices at $5,538.30 a dose as a rate comparison only. See how coverage requirements compare by payer →

Medicare pays the same ASP+6% rate for the Benlysta drug itself no matter where it's infused. The difference is what gets billed alongside it: an office infusion bills the physician fee schedule's 96365 administration code and, when documented, a separate office visit (99214), the codes used in the estimator above, while a hospital outpatient department bills its own facility fee under the hospital outpatient prospective payment system instead of those physician-fee-schedule codes. Our data doesn't carry a Benlysta-specific hospital-outpatient facility rate, so this estimator only prices the office/physician-fee-schedule path.

On a commercial plan, the BENLYSTA Copay Program lets eligible patients pay as little as $0 per dose, with an annual maximum listed only as “See program” — set at GSK's discretion; call 1-800-741-0375 for the current cap. Unlike most drug copay cards, it also reimburses up to $100 per administration for the infusion itself, except for patients living in Massachusetts or Rhode Island, who are not eligible for that part of it. It is commercial-plan only, excluding Medicare Part B/D, Medicaid, Medigap, VA, DoD, TRICARE, and state pharmaceutical assistance programs.

On Medicare it does not apply at all, and the two foundation funds that list Benlysta for lupus are both closed: HealthWell's Systemic Lupus Erythematosus fund ($15,000/year, checked June 11, 2026) and the PAN Foundation's Lupus (SLE) fund ($4,500/year, checked July 30, 2026). The GSK Patient Assistance Program ships free drug to uninsured patients but does not cover administration or an office visit, and Medicare Part D patients are not eligible even in the coverage gap. A Medigap plan is the only route to reduce the coinsurance on Medicare. See every program for this patient, with current status →

A patient who switches to the subcutaneous 200 mg autoinjector or prefilled syringe leaves this buy-and-bill claim entirely: it is a pharmacy-benefit product, priced and billed on the pharmacy side, never as a J0490 claim.

Sources: CMS ASP pricing files (Q4 2026); Medicare physician fee schedule (96365, 99214, national non-facility); Medicare Part B deductible (2026); Medicare Rights Center 2026 Medigap plan benefits chart; 37 commercial payer published price files (Q2 2026); BENLYSTA Copay Program and GSK Patient Assistance Program terms and status (public/programs-bundle.js, generated from the live programs corpus).

Reviewed September 21, 2026 by Erin Rose, CareCost Estimate founder. Methodology →