Where taxable goods are used during a return period partly in relation to taxable transaction and partly in relation to exempted or non-taxable transaction, the input tax paid or special rebate to which the dealer has become entitled to during such return period shall be apportioned between the taxable and exempted or non-taxable transactions on the basis of the ratio of taxable and exempted turnover during the period in which the input tax credit or special rebate or refund is claimed. The portion of the input tax credit or special rebate allocable to taxable sale including interstate sale shall be allowed in accordance with the provisions of section 11 or section 12, as the case may be, that allocable to stock transfer export shall be dealt with in accordance with the provisions of Rule 46 or 47 and that allocable to exempted sale or transaction shall be disallowed. Where input tax is paid on the purchase of Duty Entitlement pass book or any similar document for the import of any goods which are intended for sale, use in manufacture or use as containers or as packing materials of any taxable goods, it shall be treated as input tax paid on the goods imported and shall be dealt with accordingly.