Time limit for customs investigations: two year completion rule with a one year extension allowed for sufficient cause. Establishes a time limit requiring that inquiries or investigations leading to a notice under section 28(1) or 28(4) be completed by issuance of that notice within two years of initiation (audit, search, seizure or summons), with a possible one year extension by the Principal Commissioner or Commissioner for sufficient cause recorded in writing; excludes periods of court/tribunal stay and time to obtain overseas information; does not apply to proceedings begun before assent to the Finance Bill, 2021.