Renunciation of citizenship is most straightforward in those countries which recognize and strictly enforce a single citizenship. Thus, voluntary naturalization in another country is considered as "giving up" of one's previous citizenship or implicit renunciation. For practical reasons, such an automatic renunciation cannot officially take place until the authorities of the original country are informed about the naturalization. In Japan, a formal report is required from the renouncing person to be submitted at an embassy. Germany actively investigates whether its citizens living abroad have naturalized there when they apply for a passport; for instance in Canada, German passport applicants have to submit a search of citizenship record. Canada and Australia are signatories to the United Nations Convention on the Reduction of Statelessness, and renunciation is possible only if it will not result in statelessness. Applications for renunciation of citizenship need to be submitted in those countries with a waiting time of several months until approval.