Delegation of Commissioner's powers permits assignment to specified ranks, limiting delegation for enforcement, assessment and special commissioner functions. The Commissioner may delegate statutory functions to subordinate officers subject to minimum rank thresholds: general delegation to officers not below Assistant Value Added Tax Officer; enforcement and assessment powers to officers at or above Value Added Tax Officer; inspection powers to officers at or above Value Added Tax Inspector; and specified high-level functions to an officer designated as Special Commissioner, reflecting a designation amendment replacing the previous title.