S. 153B: Assessment-Search-Limitation-Extension of limitation period due to a reference made to foreign authorities under a tax treaty-Reference must be valid under the specific provisions of the relevant protocol-Following search in AMQ group, Assessing Officer made FT&TR reference seeking Hong Kong information for assessment year 2017-18, since India-Hong Kong DTAA effective 30-11-2018 permitted exchange only for subsequent fiscal years, such reference was impermissible and no limitation extension under Explanation (ix) to section 153B was available-DTAA-India-Hong Kong. [S. 147, 148,260A Art. 26]