Advance-payment relief: early tax payment yields deduction; delayed filing or payment attracts a fixed interest charge. The new section provides that a taxpayer who files a return before the assessment year and pays tax determined by assessment or on the return before that date gets a one per cent deduction on tax and surcharge; taxpayers who fail to file or to pay by that date are liable to interest at two per cent per annum from that date until assessment, with interest calculated on tax payable after credit for tax already paid; amounts paid to obtain the deduction are treated as tax payments and credited in the regular assessment.