Capital gain recalculation required when authoritative reduction of compensation triggers assessment amendment under tax procedure. Sub-section (16) obliges the Assessing Officer to amend any assessment computing capital gain on compensation or consideration determined or approved by the Central Government or the Reserve Bank of India where a court, Tribunal or other authority later reduces that compensation, recomputing capital gain on the reduced amount and applying section 154 with a four-year amendment period from the end of the previous year in which the reducing order was passed. Sub-section (17) permits amendment where a deduction under section 80RRB for patent royalty was allowed but the patent is later revoked or the assessee's name removed, deeming such deduction wrongly allowed and enabling recomputation under section 154 within the four-year period reckoned from the end of the relevant previous year.