Return filing obligations require electronic periodic returns, tax payment with filing, limited rectification rights, and supervisory extensions. Periodic return filing obligations require registered persons, subject to exemptions, to furnish electronic returns of supplies, input tax credit and tax payable within prescribed timeframes; distinct filing cycles apply to presumptive taxpayers, TDS deductors, Input Service Distributors and non-resident registrants. The Commissioner may extend filing deadlines by notification. Tax due must be paid by the filing date, returns must be filed for every tax period even when no supplies occurred, and omissions or incorrect particulars may be rectified in subsequent returns subject to interest and a statutory cutoff preventing late rectifications; filing for a period is barred if earlier returns remain unfiled.