National Average Drug Acquisition Cost

We update the National Average Drug Acquisition Cost (NADAC) data and comparison data weekly. Each month we post new data, including findings from the previous month’s survey and weekly price changes that have occurred before the release of the next month’s NADAC data.

Beginning with the December 2024 monthly NADAC rate updates, which will be effective 12/18/2024, CMS is implementing a temporary, short-term measure intended to address recent rate volatility occurring as a result of fluctuations in survey participation.  Specifically, monthly NADAC updates for generic drugs will be calculated using a three-month moving average.  This three-month moving average will utilize the individual calculated monthly average acquisition costs from the most recent three months and become the updated generic NADAC rate.  CMS is adopting a three-month moving average in order to moderate monthly rate volatility while also ensuring that rates remain responsive to change in market conditions.

The three-month moving average approach will not be applied to NADAC rates for brand drugs.  Brand drugs utilize a separate time frame for monthly rate calculations and the application of a moving average methodology is not necessary to prevent rate volatility at this time.

The use of the three-month moving average for generic drugs will continue until further notice.  To address the potential for future rate volatility on a more permanent basis, CMS plans to solicit stakeholder input regarding the NADAC methodology. 

The NADAC Monthly file is produced on the first Monday on or after the 15th of each month. All other files during the calendar month are weekly postings.

For more information on the fields in the NADAC data, please review the NADAC Data Field Definitions. Find more NADAC information on the Survey of Retail Prices page.