The 2016 Australian federal election in the Senate was part of a double dissolution election held on Saturday 2 July to elect all 226 members of the 45th Parliament of Australia, after an extended eight-week official campaign period. It was the first double dissolution election since the 1987 election and the first under a new voting system for the Senate that replaced group voting tickets with optional preferential voting. A number of initially-elected senators were declared ineligible a result of the 2017–18 Australian parliamentary eligibility crisis, and replaced after recounts.