UPI PIN (UPI Personal Identification Number) is a 4 to 6-digit secret code that you create/set when you first register with this app. You must enter this UPI PIN to approve all bank transfers. If you have already set up a UPI PIN for other UPI Services, you can use the same for Bharat Interface for Money (BHIM) Banks given MPIN are different from the UPI PIN. Please use the Bharat Interface for Money app to create a new UPI-PIN.