外幣債務如何履行？

在中國堅定不移推進高水平對外開放的背景下，私人交易有越來越多的可能會牽涉到外幣債務。但是，關於“外幣債務如何履行”，既有觀點在給付標的、債務範圍、履行替代等方面存在重大爭議。故而，有必要立足於《民法典》第514條建構外幣債務履行的教義學規範體系，回應實踐問題，填補理論缺失。因為金錢債務的財產價值與給付標的具有可分離性，所以，應以允許變更給付標的之簡單外幣債務作為構建任意性規範的基礎。由債務人決定給付標的變更的比較法立場缺乏充足理據。《民法典》第514條交由債權人變更給付標的之規範模式，有助於阻卻當事人的投機行為。相較於實際支付日方案、債權人有限選擇的修訂方案，根據債務屆期日的通行匯率劃定債務範圍可維持債務關係的穩定。外幣債務可以與其他金錢債務抵銷，除非被動債權的可替代性已被排除。

Against the backdrop of China's unwavering commitment to advancing high-level openingup, private transactions are increasingly likely to involve foreign currency debt. However, there are significant disputes over the issues of the subject matter of payment, the scope of debt, and the alternatives for performance regarding the question of “how to discharge a foreign currency debt.” Therefore, it is necessary to construct a doctrinal normative system for the performance of foreign currency debt based on Article 514 of the Civil Code to address practical issues and fill theoretical gaps. Since the property value of monetary debt is separable from the object of performance, the foundation for constructing discretionary norms should be the concept of simple foreign currency debt, which allows for changes in the object of performance. The comparative law position that grants the debtor the right to change the object of performance lacks sufficient justification. The normative model under Article 514 of the Civil Code, which grants the creditor the right to alter the object of performance, helps prevent opportunistic behavior by the parties. Among various approaches—such as the actual payment date scheme and a revised scheme that limits the creditor's choice—determining the scope of the debt based on the prevailing exchange rate on the due date better maintains the stability of debt relationships. Foreign currency debt can be offset against other monetary debts unless the substitutability of the passive claim has been explicitly excluded.