starting new business

This is allowed in case of multiple business divisions. Suppose you have two business, one a depatmental store store and another is a driving school. You can have two separate GSTIN for different business units. "GSTIN is a 15 digit number, and the 13th digit is the business unit number, that too in one state", if you have multiple businesses in multiple state, the first two digits will also change. 

07                              AAACA0756G                      1                                 Z                          N 

state code                pan number      intinty number of same pan       by defalt        check sum digit