Advance tax obligations require staged instalments by due dates; exemptions for senior non-business taxpayers and presumptive filers. Advance tax under Section 211 applies where tax for the year meets the threshold and covers all taxpayers. Instalments must be paid by specified due dates in the financial year, with the final instalment due before year end. Resident senior citizens without business or professional income are exempt from advance tax. Taxpayers assessed on a presumptive basis may pay the entire advance tax in a single instalment by the final due date. Payments on or before 31 March are treated as advance tax for that year. Orders served after due dates require payment on remaining instalment dates.