GSTIN

A GSTIN is the number the GST system knows your business by. It is built from your state's code and your PAN, so one PAN can hold a separate GSTIN in each state where it is registered. It goes on every tax invoice you issue, and your customers who are businesses need it to claim back the GST they paid you.

Having a GSTIN means you charge GST on your sales, claim input tax credit on your purchases (unless you choose the composition scheme), and file returns on the dates that come with your registration — even in a month with no sales.