Section 43B payment rule prevents deduction for unpaid service tax, altering taxable income and accounting timing.
Section 43B's payment-based rule makes deductions allowable only on actual payment; applied to service tax, unpaid service tax not remitted before the return filing due date is disallowable and may be treated as part of assessee's income, despite not being charged to profit and loss. Under mercantile accounting service tax received must be included in turnover, and legislative changes to payment schedules affect compliance timing; precedents reinforce that non-payment precludes deduction under the non-absentee payment requirement of Section 43B.