Time limit for completion of assessment: statutory timelines, extensions and exclusions govern reassessment and recomputation processes. Time limits for assessment, reassessment and recomputation are prescribed, with specific limitation periods for orders under the assessment provisions, special time limits for orders made to give effect to appellate or revision findings, and an extension where a transfer pricing reference is made. The statute allows the Assessing Officer limited time to implement appellate or revision orders, permits a discretionary further extension where necessary, exempts certain classes of consequential assessments from general limitations, and enumerates periods which are excluded in computing limitation, with provisos ensuring minimum residual periods.