Limitation periods and exclusion of stay periods govern GST tax determination, preserving interest and penalty adjustments. Periods during which notice service or order issuance is stayed are excluded from limitation calculations, and time consumed in appellate proceedings on revenue prejudicial issues is similarly excluded. If an appeal finds charges of fraud or wilful misstatement unsustained, the proper officer shall determine tax treating the case as an ordinary assessment. Orders following appellate directions must be issued within two years. Procedural safeguards include written hearing requests, limited adjournments with reasons, mandated statement of facts and reasons in orders, caps on demands to notice grounds, mandatory interest on short paid tax, recalculation of interest and penalty after modification on appeal, separate recovery for unpaid self assessed tax, and prohibition on duplicate penalties for the same act.