Advance tax instalment schedule requires staged payments by prescribed quarter dates; presumptive taxpayers may pay annually. Advance tax is computed on expected annual tax liability and paid in prescribed instalments through challan ITNS 280; general assessees remit staged payments by the quarter ending dates in June, September, December and March, while assessees under the presumptive taxation regime may pay the entire advance tax by the final due date. Payments on or before the last day of the financial year are treated as advance tax for that year.