These latter observations serve to indicate that a too literal understanding of the expression "exchange loss" may tend to obscure the problem in the case by suggesting that the fundamental question is whether the taxpayer has actually exchanged an amount in one currency for its equivalent in another. But the fact that, in such a case, the trader obtains an equivalent in foreign currency denies that the transaction, at that stage, results in a loss. His loss, as already pointed out, occurs when he discharges an overseas liability contracted at a time when the rate of exchange was less unfavourable to him. Likewise, he may incur an "exchange loss" as a payee. If an Australian trader were to sell goods on credit to a United States buyer for a specified number of dollars payable in Australia he would incur such a loss, if before payment, the rate of exchange were to move in favour of Australia. Initially, the sale price would be taken into his accounts in Australian currency at the rate of exchange prevailing at the date of the sale. But, although upon payment he would be paid the equivalent of the specified number of dollars, he would be entitled to receive and would actually receive a lesser sum in Australian currency than that originally taken into account. (Anderson v. Equitable Assurance Society of the United States [1] , Ottoman Bank of Nicosia v. Chakarian [2] , Cummings v. London Bullion Co. Ltd. [3] , In re Russian Commercial and Industrial Bank [4] , and in Re United Railways of the Havana and Regla Warehouses Ltd. [5] .) To my mind the defect in the respondent's argument is that it selects as its basis an expression - "exchange loss" - which is no more than a commercial term conveniently used to denote some of the effects which fluctuating rates of exchange may produce in trading transactions and then, after giving a too literal meaning to the expression, it denies that any such loss can occur except in the case of a trader who has exchanged a sum in one currency for its equivalent in another. The problem is, however, considerably wider than the literal meaning of that expression would appear to suggest to some minds. But it cannot be solved in the manner initially suggested on behalf of the appellant. At the outset of the appeal it was suggested that the mere fact that in 1936 the appellant's dollar liability to the old supplier, expressed in terms of Australian currency, had by adjustment in its books assumed a magnitude in excess of the cost at which its supplies had originally been taken into account establishes that an "exchange loss" was made. But mere entries in books of account do not create "exchange losses" although they may, in appropriate circumstances, reveal them. What we are concerned with are not merely entries in books of account; the critical question is whether, in making the two final payments, the appellant incurred losses or outgoings within the meaning of s. 51. To my mind the answer to this question must, in the circumstances of the case, be answered in the affirmative, for the difference between the amount at which its cost for stock was originally taken into account and the cost of discharging its liability, both being expressed in terms of Australian currency, truly represented an additional cost incurred in carrying on its business. The use of a trader's own dollar funds to discharge a dollar indebtedness overseas means, of course, that the trader is no longer in a position to convert the dollars used to Australian currency. And, expressed in terms of that currency, he incurs an additional cost which is just as real and significant as if it had been necessary for him to expend Australian currency to secure dollar funds for the purpose of making the payment in question. The truth of this proposition may, I think, be demonstrated by a simple illustration. An Australian trader sells goods in New York on 30th June and contemporaneously receives there the sum of a million dollars as the purchase price. Hypothetically, the rate of exchange that day is four dollars to the £A. For the purposes of Australian income tax he will, therefore, be required to bring into account the sum of £A.250,000 as assessable income. But if, on 30th June, he owes in New York the sum of 1,000,000 dollars for goods purchased six months previously - when the rate of exchange was five dollars to the £A - he may use his 1,000,000 dollars credit to discharge this liability. If he does he will be left without any dollars to remit to Australia. But, unless the view which I have expressed be correct he would be required, for income tax purposes, to bring into account as assessable income the sum of £A.250,000 and would obtain no deduction in respect of his purchases over and above the sum of £A.200,000 which was his cost, or estimated cost, at the time when he made them. This would mean, of course, that although he had received 1,000,000 dollars in New York and had expended the whole of that amount there on the same day to pay for his earlier purchases, he would be treated as if he had retained a surplus, expressed in Australian currency, of £50,000.