Determination of tax evasion: notice requires payment of tax, interest and enhanced penalties; prompt payment can conclude proceedings. Where fraud, wilful misstatement or suppression results in tax shortfall, refund or incorrect input tax credit, the proper officer issues a show cause notice requiring payment of the specified tax, interest under section 50 and a penalty. A taxpayer may avoid notice by voluntarily paying tax with interest and a reduced penalty; if accepted, no notice is issued for that amount. Notices may be followed by statements deemed as notices for related periods when grounds (except fraud or suppression) are the same, and payment within prescribed short periods after notice or order can terminate proceedings subject to higher prescribed penalties.