Determination of tax: stay periods and appellate directions affect time limits and recalculation of tax and penalties. General rules set that stay periods are excluded from computation of assessment time limits; where fraud allegations in a stricter notice fail on appeal, the proper officer must determine tax as if a standard notice were issued; appellate directions must be implemented within two years; hearings, limited adjournments with reasons, statement of findings in orders, prohibition on demands beyond notice grounds, adjustment of interest and penalty on appellate modification, recoverability of unpaid self-assessed tax, and prevention of duplicate penalties are required.