Withdrawal of appeals and waiver of remedies triggers settlement certification and precludes further challenge of the tax arrear. Section 4 requires filing the declaration before the designated authority in prescribed form; issuance of the section 5(1) certificate deems pending appeals withdrawn. Declarants must withdraw higher court writs and arbitration or mediation claims and furnish proof with payment intimation under section 5(2), and provide an undertaking waiving rights to pursue remedies in respect of the tax arrear. A declaration is void if material particulars are false, conditions are violated, or the undertaking is breached, causing revival of withdrawn proceedings and Income-tax consequences.