Selection for scrutiny: mandatory case categories and randomized sampling determine corporate assessees' tax audit selection under income tax instructions. Procedure prescribes compulsory scrutiny categories-public sector undertakings and banks; cases with sustained appellate additions/disallowances; search and seizure cases; survey cases; information-driven cases from other agencies or credible departmental evidence of evasion; and high value international transactions. Additionally, companies are split into two paid up capital bands, alphabetised, and sampled at fixed intervals with higher sampling intensity for larger paid up capital companies and lower intensity for smaller ones.