Determination of tax evasion triggers notice, staged payment options and penalties that can conclude assessment proceedings. Determination of tax involving fraud, wilful misstatement or suppression of facts requires a show cause notice demanding tax, interest under section 50 and a penalty equivalent to tax; the officer must issue notice at least six months before the time limit, may serve supplementary statements for related periods, and assessments must be completed within five years from the annual return due date or erroneous refund date. Staged pre payment options with specified reduced penalties allow conclusion of proceedings if paid within prescribed timelines, and certain proceedings (including prosecution/confiscation) are excluded from the phrase concluding proceedings.