Determination of tax: exclusion of stay periods and appellate modifications adjust tax, interest and penalty consequences. Stay periods are excluded in computing limitation periods for reassessment; appellate delays prejudicial to revenue are also excluded. If an appellate body holds that fraud or wilful misstatement was not established for a notice issued on that basis, the proper officer must determine tax treating the case as if assessed under the alternate provision. Orders required by appellate direction must be issued within two years. Officers must grant hearings on written request, record reasons for adjournments (limited to three), and set out facts and basis of decisions; appellate modifications adjust interest and penalty accordingly.