Return filing obligations require electronic GST returns with specified periods, payment due on filing, rectification limits and blocked filing. Every registered person, subject to enumerated exceptions, must furnish electronic returns for each tax period stating supplies, input tax credit, tax payable and paid within prescribed deadlines; the Commissioner may extend filing dates for specified classes. Tax due must be paid by the last date for filing. Returns must be filed for every period even if nil. Post-filing omissions or incorrect particulars (excluding matters discovered through official scrutiny, audit, inspection or enforcement) may be rectified in a subsequent return subject to interest and a statutory cut-off; filing is barred while earlier period returns remain outstanding.