The members of the Chamber of Representatives and the directly elected members of the Senate are elected by all Belgian citizens who are not less than 18 years old and who don't fall into any of the categories of exclusion determined by law. Article 61 further stipulates that each voter has only one vote. In principle, there is a federal election every 4 years, but it is possible that the Federal Parliament is dissolved early and that thus early elections are held. In order to be eligible for election one must have the Belgian nationality, have the full enjoyment of civil and political rights, be at least 21 years old and be resident in Belgium. No other condition of eligibility can be imposed.