51. Issue of Tax Demand Notice. (1) If any sum is payable by a person under the Act or these rules, the designated officer shall serve a notice in Form VAT - 56 upon him specifying the date, not less than fifteen days and not more than thirty days from the date of service of the notice, on or before which, payment shall be made and he shall also fix a date on or before which, the person shall furnish the treasury challan in proof of such payment. (2)  When the Treasury Challan is produced, the designated officer shall make the necessary entry in the personal account of the person.