The registration threshold for GST is 20 lakh rupees. Any business with an annual turnover equal or more than this amount must register for GST and pay tax. This also includes those businesses who were not registered under the older (VAT) tax regime because of its high threshold limit.
Businesses who have migrated from VAT to GST and want to claim a refund for the tax paid on old stock must file TRAN-1 form. However, those businesses who were not registered before GST and do not have bill/invoices for the tax paid on their old stocks will have to file TRAN-2.