Stamp duty value deemed consideration for land or building transfers, with tolerance rules and residential unit exceptions. Section 43CA deems the stamp duty value adopted or assessable by a State authority for land or building transfers to be the full value of consideration for computing business income when actual consideration is lower; an override proviso allows actual consideration to prevail if it exceeds a prescribed tolerance, with a higher tolerance for certain residential unit transfers subject to first-allotment and consideration conditions. Provisions of section 50C apply for value determination; where agreement and registration dates differ, the stamp duty value on the agreement date may be used if consideration was received by prescribed non-cash modes on or before that date. 'Residential unit' is defined within the section.