Period of limitation exclusions in tax assessments suspend limitation during specified administrative, investigatory, and reference processes. Explanation 1 to Section 153 lists specific periods to be excluded when computing the period of limitation for income tax assessments. Exclusions include time for reopening or re hearing of proceedings, court stays until certified vacation is received, periods for withdrawal of approvals, directions for audit or inventory valuation until reports or court vacating orders are received, references to Valuation Officers until reports are returned, declaration of identical legal questions pending higher courts, Settlement Commission and advance ruling application timelines, exchange of information requests, references under anti avoidance provisions, and the interval from search or requisition to handing over seized or requisitioned material to the jurisdictional Assessing Officer.