How Medicaid pays for generic drugs

Medicaid paid for about 757 million prescriptions in federal fiscal year 2024. Generics accounted for 85.8 percent of them, according to data compiled by the Medicaid and CHIP Payment and Access Commission (MACPAC)¹, but only 14.0 percent of the program's $106.4 billion in gross drug spending, a companion MACPAC exhibit shows².

Those gross figures overstate what Medicaid actually pays. Every manufacturer whose drugs Medicaid covers owes a rebate on every unit, the rebate grows when a price climbs faster than inflation, and federal limits cap what states pay pharmacies for many generics. For generics, the inflation piece is just under a decade old, added by Congress in 2015 after a run of sharp generic price increases.

CMS's own worked example of the generic inflation rebate shows how those rules apply to generics, and GxRadar's price history for one drug that spiked just before the rule's baseline was set shows why the timing mattered.

Generics in Medicaid, by the numbers

The split is close to a mirror image. Generics fill most prescriptions, and brands take most of the money. Spending is also rising. KFF reported in March 2026³ that net Medicaid spending on prescription drugs grew 46 percent between fiscal years 2019 and 2024, and that drugs made up 6 percent of total Medicaid spending in 2024.

How the rebate program works

The Medicaid Drug Rebate Program lives in Section 1927 of the Social Security Act, added by section 4401 of the Omnibus Budget Reconciliation Act of 1990. Its rebate agreement requirements apply to drugs dispensed and paid for under Medicaid on or after Jan. 1, 1991, as a 1995 Federal Register rule on the program⁴ recounts. All 50 states and the District of Columbia cover outpatient drugs through it, KFF notes³.

A manufacturer that wants Medicaid to cover its drugs signs a national rebate agreement with the federal government, reports prices for all of its covered outpatient drugs and pays rebates each quarter on the units Medicaid paid for. In return, states generally must cover its drugs. Rebates are calculated from the average manufacturer price, or AMP, which manufacturers report to CMS for drugs sold to retail community pharmacies. GxRadar's comparison of WAC, AWP, NADAC, MAC, FUL and ASP shows where AMP sits among the other benchmarks.

Medicaid sorts drugs into categories, and generics fall into the non-innovator multiple source category, labeled N. For N drugs, the basic rebate is 13 percent of AMP³, with no best-price provision. Brand-name drugs owe the greater of 23.1 percent of AMP or the difference between AMP and the manufacturer's best price, broadly the lowest price it gives other buyers, with statutory exclusions.

The 2015 inflation rebate for generics

Brand manufacturers had long owed an extra rebate when their prices outpaced inflation. Generics did not. In December 2015, the HHS Office of Inspector General estimated⁵ that if the penalty had applied to the top 200 generics in Medicaid, the program would have collected about $1.4 billion more in rebates from 2005 through 2014.

Section 602 of the Bipartisan Budget Act of 2015, signed Nov. 2, 2015, closed that gap. It extended the additional, inflation-based rebate to N drugs starting with the quarter that began Jan. 1, 2017. CMS set out the mechanics in Release No. 97 to manufacturers in April 2016⁶.

• For a generic marketed on or before April 1, 2013, the baseline is its AMP for the third quarter of 2014, indexed to the September 2014 consumer price index (CPI-U).
• For a generic marketed later, the baseline is its AMP in the fifth full calendar quarter after it reached the market.
• Each quarter the baseline AMP is inflated by CPI-U. If the current AMP is higher, the manufacturer owes the difference per unit on top of the 13 percent basic rebate.

Release No. 97 includes a worked example⁶, reproduced below.

In the example the drug's AMP rose about 46 percent from its baseline while CPI-U barely moved, so the inflation rebate came to more than twice the basic rebate. Together they equaled about 44 percent of the current AMP.

For years the total rebate was capped at 100 percent of AMP. KFF notes³ that as of Jan. 1, 2024, there is no longer a cap, so a drug with very large cumulative price increases can now owe more in rebates than its AMP.

Why the 2014 baseline matters

Choosing the third quarter of 2014 as the baseline for older generics meant that increases taken before then were built into the starting point. GxRadar's NADAC file for digoxin 125 mcg tablets shows what that looked like for one drug. NADAC measures what pharmacies pay, which differs from AMP, so these figures show timing only and were not inputs to any rebate.

Source: GxRadar analysis of CMS NADAC files via data.medicaid.gov¹⁰. The acquisition cost rose more than eightfold between November 2013 and January 2014, then drifted down. A rebate measured against a 2014 baseline would not reach the earlier jump; it applies to increases after the baseline. GxRadar's history of the generic price spikes of 2013 to 2015 covers the wider episode, and the price pages chart the full NADAC series for 47 generics.

What Medicaid pays the pharmacy

Rebates flow from manufacturers. On the other side of the transaction, federal rules limit what Medicaid pays pharmacies.

For many generics the limit is a Federal Upper Limit, or FUL. Under 42 CFR 447.514⁸, CMS sets one when FDA rates at least three products as pharmaceutically and therapeutically equivalent (A-rated, in the terms explained in therapeutic equivalence codes). The formula is 175 percent of the weighted average of the most recent monthly AMPs for those products. If that would fall below the average retail pharmacy acquisition cost from the most current national survey, CMS raises the FUL to match, and CMS uses NADAC⁷ for that check. How that survey is built is described in how NADAC is calculated.

A FUL limits a state's total spending on a drug and does not cap individual claims. States can pay using NADAC or their own maximum allowable cost lists, so long as total spending stays within it. CMS updates FULs monthly; the current version, based on the Affordable Care Act, took effect April 1, 2016, and states have up to 30 days after each effective date to put them in place, according to CMS⁷.

For drugs without a FUL, 42 CFR 447.512⁹ sets a different ceiling: in the aggregate, states may pay no more than the lower of the pharmacy's actual acquisition cost plus a professional dispensing fee or the pharmacy's usual and customary charge to the general public. Since the same 2016 rule, states paying pharmacies directly have had to base ingredient payments on actual acquisition cost and add a dispensing fee. The usual and customary charge is the cash price, the number GxRadar's guide on asking for the cash price helps patients find.

With the rebate cap gone since 2024, the generics where the inflation rebate bites hardest are older ones whose prices have climbed steadily since their 2014 baseline. On the payment side, CMS posts a new FUL file every month.