Interest for deferment of advance tax: shortfalls in instalments attract prescribed simple interest and limited exemptions. Interest for deferment of advance tax makes an assessee liable to pay interest on shortfalls in advance tax instalments measured against the tax due on the returned income, with prescribed instalment benchmarks and interest rates, safe-harbour payment thresholds for early instalments, a uniform simple interest rule for certain declarants at the March instalment, and exemptions from interest where shortfalls arise from underestimation of specified income categories so long as tax on those incomes is subsequently paid.