Any person of payment ,deduct income tax on the estimated income of the employee under the head 'Salaries' for that financial year .The tax is to deducted at the average of income tax computed on the basis of the rates in force for the financial year in w3hich the payment is made .In other words ,the total tax to be deducted ,on the estimate income of the employee for the relevant financial year ,is divided by the number of months of his employment during that financial year .The amount so arrived at is the monthly deduction of tax at source .No tax will , however ,be required to be deducted at source in any case unless the estimated salary income including the value of perquisites ,exceeds-