Signature
URA = max(AMP - BP, 0.231 * AMP) + max(AMP - AMP_b * CPI_t / CPI_b, 0)
| Inputs | Definition | Unit |
|---|---|---|
AMP | AMP for the dosage form and strength in the rebate period | dollars per unit |
BP | Lowest price available from the manufacturer to any wholesaler, retailer, provider or other purchaser in the United States, excluding statutory exemptions | dollars per unit |
AMP_b | AMP in the quarter beginning 1 July 1990, or in the first full quarter after the drug was first marketed | dollars per unit |
CPI_t | CPI-U for the month before the month in which the rebate period begins | index points |
CPI_b | CPI-U for September 1990, or for the month before the first full quarter after first marketing | index points |
URA | Medicaid rebate per unit, basic plus additional | dollars per unit |
|---|
Function
340B ceiling price function
Maps a covered outpatient drug's average manufacturer price and its Medicaid unit rebate amount for the preceding calendar quarter to the maximum price a covered entity can be required to pay for the smallest unit of the drug. The statute sets the ceiling as AMP reduced by the rebate percentage, the Medicaid rebate per unit divided by AMP, which is AMP minus the unit rebate amount.
Implementations
Excel
Unit rebate amount from AMP, best price and CPI-U
With the inputs in AvgMfrPrice, BestPrice, BaseAMP, CPICurrent and CPIBase, Excel returns the basic plus additional rebate per unit.
=MAX(AvgMfrPrice-BestPrice,0.231*AvgMfrPrice)+MAX(AvgMfrPrice-BaseAMP*CPICurrent/CPIBase,0)
Assumptions
Single-source or innovator multiple-source drug
The 23.1% minimum applies to these drugs for rebate periods after 31 December 2009. Clotting factors and drugs approved exclusively for paediatric indications have a 17.1% minimum, generic drugs follow a different rebate under section 1927(c)(3), and line extensions of oral solid drugs have a further alternative calculation.
Rebate periods from 1 January 2024
The statute capped the basic and additional rebates together at 100% of AMP only for rebate periods before 1 January 2024. For earlier quarters the total is capped at AMP.
Worked examples
Branded drug with no inflation rebate
Using the article's figures, a drug has an AMP of 100 dollars and a best price of 85. Its base-period AMP of 95 dollars, uprated by a CPI-U rise from 300 to 330, is 104.50, above the current AMP, so there is no additional rebate. The URA is the minimum rebate of 23.10 dollars. The CPI values are illustrative.
AMP = 100; BP = 85; AMP_b = 95; CPI_t = 330; CPI_b = 300; URA = 23.10
Branded drug with an inflation rebate
The same drug launched at a base AMP of 60 dollars when the CPI-U stood at 250, with the index now at 320. The uprated base AMP is 76.80, so the additional rebate is 23.20 and the URA 46.30 dollars. The figures are illustrative.
AMP = 100; BP = 85; AMP_b = 60; CPI_t = 320; CPI_b = 250; URA = 46.30
Inflation rebate large enough to exceed AMP
A drug launched at 10 dollars when the CPI-U stood at 150, now priced at 100 with the index at 330, has an uprated base AMP of 22 and an additional rebate of 78. The URA of 101.10 dollars exceeds AMP, and the ceiling price falls to the 0.01 dollar floor. The figures are illustrative.
AMP = 100; BP = 85; AMP_b = 10; CPI_t = 330; CPI_b = 150; URA = 101.10
Common errors
Using only the 23.1 per cent minimum for all drugs
Ignoring the inflation rebate sets the URA at 23.10 dollars in the second example instead of 46.30, and the ceiling price at 76.90 instead of 53.70, overstating 340B prices for drugs whose prices have risen faster than inflation.
Applying the 100 per cent cap to recent quarters
The cap on total rebates at 100% of AMP ended for rebate periods beginning on or after 1 January 2024. Capping the URA at AMP for later quarters hides the penny pricing that follows.
Sources
Medicaid rebate formula
United States Code, Title 42, section 1396r-8. Payment for covered outpatient drugs (Social Security Act section 1927). Accessed 29 September 2026. Subsection (c)(1)(A) (basic rebate: greater of AMP minus best price and the minimum rebate percentage of AMP), (c)(1)(B)(i)(VI) and (iii) (23.1% after 31 December 2009; 17.1% for listed drugs), (c)(1)(C) (best price), (c)(2)(A) and (B) (additional rebate for AMP increases above CPI-U from the base quarter) and (c)(2)(D) (100% of AMP cap for rebate periods before 1 January 2024).
Rebate percentage link to the 340B ceiling
United States Code, Title 42, section 256b. Limitation on prices of drugs purchased by covered entities (Public Health Service Act section 340B). Accessed 29 September 2026. Subsection (a)(2)(A): the rebate percentage is the average total rebate required under section 1927(c) for a unit, divided by AMP.
Canonical Identity
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