Part B National Summary Data File (Previously known as BESS)

Help Us Improve the National Summary File

Date: 03/13/2026

Data File available for 2024 (contact us for previous years)

CMS is soliciting feedback from users of the Part B National Summary File. If you currently use this data, or have need of data files prior to 2024, please contact ipag_data_products@cms.hhs.gov and we will assist you.

Please be advised that these files contain material that is copyrighted by the American Medical Association. Before you download the files you must read, agree to, and abide by the provisions of the copyright statement via the "AMA Click Agreement".

The data sets are summarized by meaningful Healthcare Common Procedure Coding/Current Procedural Terminology, (HCPC/CPT), code ranges. Brief descriptions for the code ranges and modifiers are provided in the readme file. The data set name contains the year followed by a five character sequence that is the HCPC/CPT code. This HCPC/CPT code corresponds to the first HCPC/CPT in the selected code range of disciplines. Within each code range are, procedural, condition, or description subheadings. Each data set displays the allowed services, allowed charges, and payment amounts by HCPC/CPT codes and prominent modifiers. These reports will only illustrate the modifiers where duplicative claim submissions occur. This is to avoid duplicate counting of services. Utilization for modifiers not affected by duplicative counting are collapsed into the Other category on the reports. Therefore, not all Centers for Medicare & Medicaid Services (CMS) published modifiers are illustrated. The file is updated annually and usually available by September for the previous year.