Return filing obligations require registered persons to submit prescribed electronic returns and pay tax by due dates, with limited rectification. Registered persons must electronically furnish prescribed returns with frequency and deadlines tied to their category (monthly for regular taxpayers, ISDs and non-residents; quarterly for composition taxpayers; monthly for TDS deductors). The Commissioner may extend deadlines. Tax due as per a return must be paid by its due date. Corrections to returns are allowed in later returns subject to interest and a statutory cut-off for rectification; no return for a period may be filed while earlier period returns remain unfiled.