If a company’s yearly turnover exceeds Rs 5 crore, it is required to file two types of returns monthly under the GST system. GSTR-1 and GSTR-3B are the sources of these. The first is a return that reveals invoices for sales, while the second is for stating GST liabilities in aggregate. While GSTR-1 must be reported by the 11th of the month following the transaction, GSTR-3B must be filed by the 20th of the month after the transaction.