Determination of tax evasion: notice triggers payment with interest and prescribed penalty, with structured voluntary resolution options. Where fraud, wilful misstatement, or suppression has caused tax shortfall, erroneous refund, or wrongful input tax credit, the proper officer issues a show cause notice requiring payment of tax, interest and a penalty equivalent to the tax. The officer must issue the notice within a statutory limitation period, may serve a related statement for other periods where non-fraud grounds align with the original notice, and must determine tax, interest and penalty after considering representations; specified voluntary payments within short timelines conclude the proceedings.