Improved Master Beneficiary Summary File Now Available

CMS is pleased to announce improvements to the Master Beneficiary Summary File (MBSF) to include timely Medicare Advantage (Part C) enrollment information and Medicare Prescription Drug (Part D) enrollment information.  While the MBSF has always included all Medicare beneficiaries, the updated MBSF “Base (A/B/C/D) Segment” includes enrollment information for beneficiaries enrolled in Part C and Part D, as well as those in traditional Medicare (Parts A and B). 

The new MBSF “Base (A/B/C/D) Segment” replaces the MBSF “Base (A/B/D) Segment.” Beginning May 22nd, 2017, all MBSF base segments 2006 and forward will be in the new ABCD format.  CMS will also be updating the Cost & Use segment and will post a notice when these updated files are available. Updated data dictionaries for the ABCD segment are available at the CCW website.