Remedial action under section 263 requires PCIT to decide appropriate remedy; AO acts if 263 not invoked. When a Revenue Audit objection is accepted the Principal Chief Commissioner must decide if the order requires revision under section 263 and, if so, call for records and initiate revision; if not, the Assessing Officer must, by independent application of mind, examine each case and take suitable remedial action. If the AO opts for rectification under section 154, initiation requires Range head approval. Remedial action must be initiated and completed within prescribed short timelines, and the objection is treated as settled once completion is intimated and any demand notice issued.