Search assessments under section 153A permit full reassessment for abated years but limit reopened completed years to incriminating search material.
Section 153A's assessment power is search-linked: for abated years the AO may reassess total income afresh, but for completed/unabated years additions under section 153A are permissible only where specific incriminating material relating to that year is found during the search; absent such material, disturbance of a completed assessment must proceed, if at all, under sections 147-148 subject to their conditions.

Scope of assessment post-search: completed assessments permit additions only from incriminating material found during searches.
The Supreme Court clarified that for assessments completed before a search, the Assessing Officer's power to reassess within the retrospective period is constrained: any additions in such completed assessments must be based on incriminating material discovered during the search, thereby limiting use of search powers to matters tied to the unearthed evidence and preventing expansion of assessments on unrelated material.