TNVAT filing

as u r registered delear u need to file the tax return , its not montly its quartely return  u need to file return before 21 of jan for the quarter ended 31 dec like that , as u are collecting tax from the buyers for claiming setoff on purchase made u need to keep the purchase bill with the tax paid and all the details in tact , if u dnt you need to pay the complete tax as collected without the setoff for tax which you had paid at the time of purhcases