1. Jerman: 18+5 thn (in general)
Pengecualian:
-Spätaussiedler (Orang2 yg aslinya berdarah Jerman tapi dulunya hidup di negara lain dan karena satu lain hal ingin pulang ke Jerman.. rata-rata pengembalian dari Eropa timur, Rusia dkk, efek sisa PD II )
-Warga negara dari negara-negara yang punya policy melekatkan kewarganegaraan sampai mati dimanapun mereka berada dan situasi apapun dan karenanya jd memungkinkan penduduknya untuk memiliki kewarganegaraan ganda (Artinya mereka tidak punya pilihan untuk menolak kewarganegaraan asalnya. Ex: Brazil, Meksiko, Iran :setidaknya yg perempuan krn disana perempuan statusnya sll ikut laki-laki khususnya = suami, tdk pny hak sendiri,
2. USA
3. Belanda (idem dengan Jerman)
4. Indonesia : 18+3
5. Italy (source: Nina Striano)
6. France: ambigu (teoretis tidak diijinkan, tapi tidak ada kontrol dan pelaku pemilik illegal kewarganegaraan ganda juga tdk dihukum, source: Aneke Sandra)
6. Hongkong ? (still big question, karena sekarang Hongkong masuk wilayah China yang tidak mengakui double nationality, so it's still not clear dengan WN asli Hongkong yang sudah pernah tercatat memiliki WN ganda, dianggap illegal ataukah untuk Hongkong masih diterapkan pengecualian). Further reliable Information woould be helpful :)
7. United Kingdom:
Since the British Nationality Act of 1948, there is in general no restriction, in United Kingdom law, on a British national being a citizen of another country as well. So, if a British national acquires another nationality, they do not automatically lose British nationality. Similarly, a person does not need to give up any other nationality when they become British.
Different rules apply in the cases of British protected persons and certain British subjects. A person who is a British subject other than by connection with the Republic of Ireland loses that status on acquiring any other nationality or citizenship. Similarly, a British protected person is no longer a British protected person on acquiring any other nationality or citizenship. Although British Overseas citizens are not subject to loss of citizenship, British Overseas citizens may lose an entitlement to register as a British citizen under s4B of the 1981 Act if they acquire any other citizenship.
Many other countries, however, do not allow dual nationality . If a person has British nationality, and is also a national of a country that does not allow dual nationality, the authorities of that country may either regard the person as having lost that nationality or may refuse to recognize the British nationality. British nationals who acquire the nationality of a country that does not allow dual nationality may be required by the other country to renounce British nationality to retain the other citizenship.
Under international law, the Master Nationality Rule states that a State may not give diplomatic protection to one of its nationals in a country where the person also holds citizenship. For example, a person who is both British and American cannot receive diplomatic help from a British Consul in the United States.
A British person who acquired foreign citizenship by naturalisation before 1949 may have lost British nationality at the time. No specific provisions were made in the 1948 legislation for such former British subjects to acquire or otherwise resume British nationality, and hence such a person would not be a British citizen today. However, women who lost British nationality on marriage to a foreign man before 1949 were deemed to have reacquired British subject status immediately before the coming into force of the 1948 act.
8. Turki:
Dual citizenship (the simultaneous possession of two citizenships) is possible in Turkey because there are no uniform rules of international law relating to the acquisition of nationality. Each country has its own laws regarding nationality, and its nationality is conferred upon individuals on the basis of its own domestic policy. Individuals may have dual nationality by choice or by the automatic operation of these different (and sometimes conflicting) laws.
The laws of Turkey provide for acquisition of Turkish citizenship based on one's descent—by birth to a Turkish citizen parent (or parents) in Turkey and also by birth abroad to a Turkish citizen parent (or parents)—regardless of the other nationalities a person might acquire at birth. Children born in Turkey to foreign citizens do not have a claim to Turkish citizenship, unless one of the parents is also a Turkish citizen. The automatic acquisition (or retention) of a foreign nationality does not affect Turkish citizenship. Turkish laws have no provisions requiring citizens who are born with dual nationality to choose one nationality over the other when they become adults.
While recognizing the existence of dual nationality and permitting Turkish citizens to have other nationalities, the Turkish government requires that those who apply for another nationality inform the appropriate Turkish officials (the nearest Turkish embassy or consulate abroad) and provide the original Naturalization Certificate, Turkish birth certificate, document showing completion of military service (for males), marriage certificate (if applicable) and four photographs. Dual nationals are not compelled to use a Turkish passport to enter and leave Turkey; it is permitted to travel with a valid foreign passport and the Turkish National ID card.
9. Russia (info dari rina dalimunthe) kategori boleh dua kewarganegaraan tapi ada batasannya secara lengkap infonya belum sempat ubek internet karena aturan dan hukum Russia sering ada perubahan.
10. Jepang / Japan / 日本: 20+2.
Kewarganegaraan ganda bisa diperoleh seorang anak hasil perkawinan campuran yang mana salah satu orang tua berkewarganegaraan Jepang dan satunya kewarganegaraan lain, terbatas hingga 20 plus 2 tahun. Dua puluh adalah usia di mana kewarganegaraan ganda tersebut berakhir, dua tahun adalah tenggang waktu berpikir, menentukan kewarganegaraan mana yang akan dipilih. Untuk informasi, Jepang menganut jus sanguinis, kewarganegaraan berdasarkan orang tua, jadi jika anak anda lahir di Jepang tapi tidak satupun orang tua berkewarganegaraan Jepang, maka si anak tidak mendapatkan kewarganegaraan Jepang. Tetapi jika karena tersandung oleh hukum negara orang tua yang mengakibatkan si anak stateless (tanpa kewarganegaraan), Jepang bisa memberikan kewarganegaraan lewat registration / acquisition. Sumber di sini: http://bit.ly/1kBSHaX(tapi ini bahasa pemerintah yang kurang gamblang menurut saya), atau di sini yang lebih sederhana dan gamblang http://bit.ly/1hNxcCf
11. Meksiko
12. Lanjut....
12. Lanjut....
AK