Advance tax obligation: taxpayers must submit statements or estimates and pay tax in scheduled instalments accordingly. Advance tax requires persons likely to exceed the income threshold to send a prescribed statement or estimate of current income and payable advance tax to the Income-tax Officer and to pay that advance tax in equal instalments or, when applicable, in one sum. Taxpayers may replace statements with estimates if income is likely lower, and must furnish revised estimates and pay additional tax where current income exceeds earlier computations by more than the prescribed percentage, with a lower percentage applying to companies. The Commissioner may extend filing dates for certain businesses, and all submissions must be in prescribed form and verified. Current income excludes capital gains and specified incomes.