MAC Pricing (Maximum Allowable Cost)

MAC pricing, Maximum Allowable Cost, is the ceiling a PBM will pay a pharmacy for a generic drug, no matter which manufacturer's version the pharmacy dispensed. The PBM keeps a list, the MAC list, with one price per generic. If a pharmacy buys a version that costs more than the MAC, the pharmacy eats the difference. The idea is sound: it pushes pharmacies to buy the cheapest version of a generic.

Here is where it gets interesting. A PBM can keep more than one MAC list. One list decides what it pays the pharmacy; a different, higher list decides what it charges the employer's plan for the same pill. The gap between them is spread pricing, and MAC lists are where most of it lives. Pharmacies also complain that MAC prices lag the market: when a generic's cost spikes during a shortage, the MAC may not move for weeks, and the pharmacy loses money on every fill. More than 40 states now have laws requiring PBMs to update MAC lists within a set number of days and to give pharmacies an appeal process. Texas passed its version in 2015.

The takeaway: if you sponsor a plan, ask your PBM in writing whether the MAC list used to pay pharmacies is the same list used to bill you. If the answer is anything but a plain yes, you have found where your generic drug dollars are going.