Rebates and the gross-to-net gap
This is the single most misunderstood mechanic in US drug pricing. Understand rebates and you understand why list prices keep climbing while manufacturers swear net prices are flat — and why the cheaper drug so often loses.
Two prices for the same drug
Every brand drug effectively has two prices. The list price (WAC) is the public sticker. The net price is what the manufacturer actually keeps after paying money back to the middlemen. The difference — the gross-to-net gap, sometimes called the gross-to-net “bubble” — is enormous, often half the list price or more on brand drugs.
How a rebate works
A manufacturer wants its drug on a health plan's formulary in a good tier. The plan's PBM controls that spot. So the manufacturer offers a rebate — it pays the PBM/plan back a percentage of the list price for every unit dispensed, in exchange for favorable placement. The list price never changes; money just flows backward after the sale.
The perverse incentive
Rebates are a percentage of list. So a manufacturer can raise the list price, hand back a bigger rebate, and leave everyone in the middle better off — while the patient whose copay is calculated on the list price pays more. Higher list prices can literally be the result of competition, not the absence of it.
Who actually gets the rebate
Mostly not the patient at the counter. Rebates flow to the PBM and the plan, and are meant to lower premiums broadly. But a patient paying coinsurance — a percentage — is usually charged against the full list price, so the person taking the drug can be the one person in the chain who doesn't benefit from the discount on it.
The rebate trap
Because placement is won with rebate dollars, a high-list, high-rebate brand can beat a genuinely cheaper competitor — a biosimilar or a low-list alternative — for the formulary spot, even when the cheaper option would cost the system less overall. This is a big reason low-priced drugs and biosimilars struggle to gain traction.
Reform, slowly
Fixes in play: moving rebates to the point of sale so patients see them, forcing rebate transparency, and — under the Inflation Reduction Act — inflation rebates that claw back money when a drug's price outpaces inflation. It's also why every WAC on this site is labeled a list price, not what anyone truly nets.