Return filing obligations require electronic submission and timely payment, with rectification limits and filing blocks for outstanding periods. Registered persons must file electronic returns reporting supplies, input tax credit, tax payable and tax paid per prescribed periodicity; distinct deadlines apply by category, extensions may be notified by the Commissioner, returns must be filed for each tax period even if no supplies occurred, tax payable is due by the return date, omissions or incorrect particulars may be rectified in later returns subject to temporal cutoffs and exclusions for authority-initiated findings, and filing is blocked if earlier period returns remain unfurnished.