The new Medicare Part A Skilled Nursing Facility Prospective Payment System (SNF PPS) called the Patient Driven Payment Model (PDPM) will cover all resident days starting on October 1, 2019. PDPM requires an acceptable ICD-10 diagnosis code to be entered into MDS item field I0020B to represent the primary reason for the SNF stay. ICD-10 codes not on the list of allowable codes, often referred to as "return-to-provider" codes, will not classify into a PDPM clinical category. CMS publishes a list ICD-10 codes that are approved for use in MDS Item field I0020B for PDPM classification purposes. CMS published an updated list on August 20, 2019. If a code is not listed in this file, it cannot be used in the MDS I0020B item field. The CMS webpage file, can be found here. The CMS webpage also includes the final version of the October 1 implementation MDS 3.0 Data Specifications (V3.00.1) for software developer use.