(1) For the purposes of section 84, the capital employed in an undertaking or a hotel to which the said section applies shall be taken to be: (a) in the case of assets acquired by purchase and entitled to depreciation 591 (i) if they have been acquired before the computation period, their written down value on the commencing date of the said period; (ii) if they have been acquired on or after the commencing date of the computation period, their average cost during the said period; (b) in the case of assets acquired by purchase and not entitled to depreciation (i) if they have been acquired before the computation period, their actual cost to the assessee; (ii) if they have been acquired on or after the commencing date of the computation period, their average cost during the said period; . . . . . . . . . . . (3) Any borrowed money and debt due by the person carrying on the business shall be deducted and in particular there shall be deducted any debts incurred in respect of the business for tax (including advance tax) due under any provision of the Act: Provided that any such debt for tax (including advance tax) shall, for the purpose of this sub rule, be deemed to have become due (a) in the case of any advance tax due under any provision of the Act or of any tax payable under section 140 A or under section 141, on the date on which, under the provisions of section 211 or section 2 12 or section 2 13 or section 140 A or section 220, as the case may be, the payment first became due; (b) in any other case, on the last day of the period of time within which the tax is payable under section 220.