Return frequency flexibility: government may notify classes of taxpayers to file and pay returns quarterly subject to conditions. Section 39 is amended to substitute prescription-based timing-returns must be filed 'in such form, manner and within such time as may be prescribed,' remove the fixed monthly due-date, and allow the Government to notify classes of registered persons to furnish returns quarterly subject to conditions and safeguards; a matching proviso permits notified classes to pay tax by the return's due date; subsection (9) requires corrections in prescribed form and manner and ties the cut-off to the financial year to which details pertain.