Closed User Group (CUG) is a set of individuals brought together for a pilot study. In retail pilot of digital currency, CUG is a group of retail customers and merchants who will transact with each other using digital rupee in select locations. The Reserve Bank of India (RBI) has made this group for pilot testing of retail Central Bank Digital Currency (CBDC). As per sources, around 50,000 individuals and merchants have been selected for pilot testing. The central bank commenced first phase of retail pilot on December 1 with four banks viz. State Bank of India, ICICI Bank, YES Bank, and IDFC First Bank. Four other banks will join the pilot later.