Where service tax has not been levied or paid, or has been short-levied or short-paid, or erroneously refunded, for any reason, other than the reason of fraud or collusion or wilful mis-statement or suppression of facts or contravention of any of the provisions of this Chapter or of the rules made there under with the intent to evade payment of service tax, the person who has been served notice under sub-section (1) of section 73 shall, in addition to the service tax and interest specified in the notice, be also liable to pay a penalty not exceeding ten per cent. of the amount of such service tax.
further, on the base of your last year tournover the rate of interst decided.