An initial proposal on requirements for interoperability of physical parameterizations and associated driver was drafted by GMTB and sent to EMC and the NGGPS Program Office in November 2015. This proposal incorporated some materials produced previously by the Earth System Prediction Capability Physics Interoperability ESPC PI) team. Requirements evolved over the following year with input provided by EMC, the NGGPS Program Office, the NGGPS Physics Team, the EMC Strategic Implementation Plan (SIP) Physics Working Group, and the ESPC PI team, with the most substantial revision being done in February 2016 with input from EMC. These requirements are consistent with the Project 3: Collaborative framework for developing physical parameterizations listed in the document EMC Strategic Implementation Plan (SIP) for Evolution of NGGPS to a National Unified Modeling System. These requirements were formally accepted by the NGGPS Program Office in October 2017.