GSTR-3B is a monthly or quarterly self-declared summary return filed by taxpayers under the Goods and Services Tax (GST) regime. The purpose of the return is for taxpayers to declare their summary GST liabilities for a particular tax period and discharge these liabilities. The return is a simplified summary return and is used to report summary GST liabilities for a tax period. All normal taxpayers and casual taxpayers are required to file Form GSTR-3B. The return is divided into seven sections, and taxpayers must provide details such as their GSTIN number, the legally registered name of their business, details of sales and purchases for which they are accountable for reverse charge, and details of tax on outward and inward supplies liable to reverse charge. Taxpayers can file GSTR-3B returns from the returns section of the GST Portal. The return cannot be revised or amended once filed. Late fees or penalties are charged for filing GSTR-3B of a tax period after the due date.