Limitation period exclusion for stayed proceedings preserves computation of tax assessment timelines and affects subsequent recovery. Periods of stay or pending appellate decisions are excluded when computing limitation for issuing tax notices and orders. Notices issued under fraud provisions may be treated as general determination notices if fraud is not established. Appellate directions require timely compliance, unpaid self assessed tax is recoverable under the recovery provision, and procedural safeguards include written hearing requests, limited adjournments, reasoned orders, demand limits tied to notice grounds, proportional modification of interest and penalty, and a bar on duplicate penalties.