Determination of tax: stay periods excluded from limitation and procedures govern reassessment, hearings, recovery and penalty duplication. Periods of stay on service of notice or issuance of order are excluded from limitation for reassessment; notices under fraud provisions found unsustainable must be treated as regular reassessment notices. Orders directed by appellate bodies must be issued within two years. The taxpayer is entitled to hearing on written request; adjournments are limited and reasons must be recorded. Orders must set out facts and basis; demands cannot exceed notice grounds or amounts; interest on short-paid tax is payable whether specified in order or not. Modifications by appellate bodies adjust interest and penalty; unpaid self-assessed tax is recoverable under recovery provisions and penalties under specified sections are not duplicative.