Advance tax obligation under presumptive taxation requires full payment by the due date to avoid interest consequences. A person opting for the presumptive taxation scheme under section 44AD must pay the whole advance tax liability for the business income covered by the scheme by the statutory due date in the previous year; failure to do so attracts interest under the provisions for nonpayment and shortfall of advance tax. A tax payment made on or before the last day of the financial year is treated as payment of advance tax for that year.