Determination of tax by fraud: notice compels payment with interest and penalty to resolve proceedings. Where the proper officer finds tax not paid, short paid, erroneously refunded, or input tax credit wrongly availed or utilised by reason of fraud, wilful misstatement or suppression of facts, he shall serve a show cause notice specifying tax, interest under section 50 and a penalty equivalent to the tax. Notices must be issued at least six months before the limitation for the final order. A taxable person may prepay tax with interest and a fifteen per cent penalty to prevent a notice, pay a twenty five per cent penalty within a short period after notice to conclude proceedings, or pay a fifty per cent penalty after an order to conclude proceedings; the officer must determine amounts and issue an order within five years from the relevant annual return due date or erroneous refund date.