Is it necessary to deduct Tax at source even if one is employed for a short duration?

Is it necessary to deduct Tax at source even if one is employed for a short duration as low as one month.His salary works out to 25,000/- but was employed only for 45 days on a consultation basis.The company employed him has deducted a tax at 10 % of the total salary/compensation paid to him. The company can issue a certificate to the effect of deducting Tax. But is it correct in the situation his total salary drawn over the financial year in any case does not exceed the taxable income.