Determination of tax evasion triggers notice requiring tax, interest and penalties, with payment options to close proceedings. Where tax is unpaid, short paid, erroneously refunded or input tax credit wrongly availed by reason of fraud or wilful misstatement or suppression, the proper officer shall serve a show cause notice specifying tax, interest and a penalty equal to the tax. Voluntary payments may prevent or conclude proceedings: pre notice payment with interest and a fifteen percent penalty prevents notice; payment within thirty days of notice with interest and a twenty five percent penalty concludes proceedings; payment within thirty days of the order with interest and a fifty percent penalty also concludes proceedings. The officer then determines tax, interest and penalty and issues an order within the limitation period.