(Its Urgent) Notice U/s 143(1) By Income Tax

you must have got a copy of the intimation under section 143(1), from which you can make out what mistake the income tax department has made. you can make an application for ractification under sec. 154 of the I.T. Act alongwith all the necessary proofs to support your claim to your assessing officer. he is statutorily under obligation to dispose off your application within 6 months from the end of the month in which such application is made. if the application is rejected, or no action is taken within 6 months, you can appeal against such errornous order with the commissioner(Appeal).