Return filing requirement: registered persons must electronically file periodic GST returns within prescribed timelines, with rectification and non filing consequences. Registered persons must electronically furnish returns of inward and outward supplies, input tax credit, tax payable and tax paid for each tax period according to prescribed periodicities and timelines; payment of tax is due by the return deadline. Post filing rectification of omissions or incorrect particulars is allowed in subsequent returns subject to interest but barred after a specified post year cutoff or filing of the annual return. Filing is blocked if earlier period returns remain unfurnished; extensions may be notified for classes of persons.