Tax clearance certificate requirement restricts certain departing persons unless employer undertaking or tax authority certificate permits exit. Certain departing persons must secure tax clearance: non-domiciled persons with Indian-source income must provide an employer or payer undertaking (Form 30A) to obtain a no-objection certificate (Form 30B); domiciled persons normally furnish Form 30C but may be required, with recorded reasons and prior senior approval, to obtain a tax clearance certificate (Form 33) certifying no outstanding liabilities or satisfactory arrangements for tax payment. Owners or charterers allowing travel without required certificates may be liable and deemed assessees in default.