From Wikipedia:
Austria-Hungary, often referred to as the Austro-Hungarian Empire or the Dual Monarchy, was a constitutional monarchy in Central and Eastern Europe between 1867 and 1918. It was formed when the Austrian Empire adopted a new constitution; as a result Austria (Cisleithania) and Hungary (Transleithania) were placed on equal footing. It dissolved into several new states at the end of the First World War.
The union was established by the Austro-Hungarian Compromise of 1867 on 30 March 1867 in the aftermath of the Austro-Prussian War. It consisted of two monarchies (Austria and Hungary), and one autonomous region: the Kingdom of Croatia-Slavonia under the Hungarian crown, which negotiated the Croatian–Hungarian Settlement in 1868. It was ruled by the House of Habsburg, and constituted the last phase in the constitutional evolution of the Habsburg Monarchy. Following the 1867 reforms, the Austrian and Hungarian states were co-equal in power. Foreign and military affairs came under joint oversight, but all other governmental faculties were divided between respective states.
The division between Austria and Hungary was so marked that there was no common citizenship: one was either an Austrian citizen or a Hungarian citizen, never both. This also meant that there were always separate Austrian and Hungarian passports, never a common one. However, neither Austrian nor Hungarian passports were used in the Kingdom of Croatia-Slavonia. Instead, the Kingdom issued its own passports which were written in Croatian and French and displayed the coat of arms of the Kingdom of Croatia-Slavonia-Dalmatia on them.[24] It is not known what kind of passports were used in Bosnia-Herzegovina, which was under the control of both Austria and Hungary.
The Kingdom of Hungary had always maintained a separate parliament, the Diet of Hungary, even after the Austrian Empire was created in 1804. The administration and government of the Kingdom of Hungary (until 1848–49 Hungarian revolution) remained largely untouched by the government structure of the overarching Austrian Empire. Hungary's central government structures remained well separated from the Austrian imperial government. The country was governed by the Council of Lieutenancy of Hungary (the Gubernium) – located in Pressburg and later in Pest – and by the Hungarian Royal Court Chancellery in Vienna The Hungarian government and Hungarian parliament were suspended after the Hungarian revolution of 1848, and were reinstated after the Austro-Hungarian Compromise in 1867.
Despite Austria and Hungary sharing a common currency, they were fiscally sovereign and independent entities.
