As usual I'm not quite sure where these should go, but I think they'd be useful somewhere.
Federal
edit1901-1903
editHouse of Representatives
| Party (no majority in this parliament) | Total | Vacant | Cause | ||||
|---|---|---|---|---|---|---|---|
| Protectionist | Free Trade | Labour | Independent | ||||
| 30 March 1901 | 31 | 28 | 14 | 2 | 75 | 0 | |
| 9 May 1901 | 31 | 27 | 14 | 3 | 75 | 0 | Free Trade MP Sir Frederick Holder (SA) became an independent when he was elected Speaker. |
| 8 August 1901 | 30 | 27 | 14 | 3 | 74 | 1 | Protectionist MP William Groom (Darling Downs, Qld) died. |
| 14 September 1901 | 31 | 27 | 14 | 3 | 75 | 0 | Littleton Groom (Protectionist) won the Darling Downs by-election. |
| 6 March 1902 | 31 | 26 | 14 | 3 | 74 | 1 | Free Trade MP Frederick Piesse (Tas) died. |
| 26 March 1902 | 31 | 27 | 14 | 3 | 75 | 0 | William Hartnoll (Free Trade) won the Tasmania by-election. |
| 18 August 1903 | 31 | 26 | 14 | 3 | 74 | 1 | Free Trade leader George Reid (East Sydney, NSW) resigned to recontest his seat in protest at the new electoral boundaries for New South Wales. |
| 4 September 1903 | 31 | 27 | 14 | 3 | 75 | 0 | George Reid (Free Trade) was re-elected at the East Sydney by-election. |
| 24 September 1903 | 30 | 27 | 14 | 3 | 74 | 1 | Prime Minister and Protectionist MP Sir Edmund Barton (Hunter, NSW) resigned to take up a seat on the High Court. |
| late 1903 | 29 | 27 | 14 | 4 | 74 | 1 | Protectionist MP Thomas Macdonald-Paterson (Brisbane, Qld) lost preselection and opted to contest his seat as an independent at the forthcoming election. |
Senate
| Party (no majority in this parliament) | Total | Vacant | Cause | ||||
|---|---|---|---|---|---|---|---|
| Protectionist | Free Trade | Labour | Independent | ||||
| 30 March 1901 | 11 | 17 | 8 | 0 | 36 | 0 | |
| 2 January 1903 | 11 | 16 | 8 | 0 | 35 | 1 | Free Trade senator Sir Frederick Sargood (Vic) died. |
| 21 January 1903 | 11 | 17 | 8 | 0 | 36 | 0 | Robert Reid (Free Trade) was appointed to the Victorian Senate vacancy. |
| 17 April 1903 | 11 | 16 | 8 | 0 | 35 | 1 | Free Trade senator Norman Ewing (WA) resigned. |
| 4 September 1903 | 11 | 17 | 8 | 0 | 36 | 0 | Henry Saunders (Free Trade) was appointed to the Western Australian Senate vacancy. |
| 24 September 1903 | 10 | 17 | 8 | 0 | 35 | 1 | Protectionist senator Richard O'Connor (NSW) resigned to take up a seat on the High Court. |
| 8 October 1903 | 11 | 17 | 8 | 0 | 36 | 0 | Charles Mackellar (Protectionist) was appointed to the New South Wales Senate vacancy. |
2010-2013
editHouse of Representatives
| Party (no majority in this parliament) | Total | Vacant | Cause | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Labor | Coalition | Greens | KAP | Inds | ||||||||
| Liberal | LNP | Nationals | CLP | Total | ||||||||
| 21 August 2010 | 72 | 44 | 21 | 7 | 1 | 73 | 1 | 0 | 4 | 150 | 0 | Note: The National Party of Western Australia, while part of the National Party, is not part of the Coalition. Its sole MP, Tony Crook (O'Connor, WA), initially sat on the crossbenches before joining the National party room on 2 May 2012; he still does not attend joint Coalition meetings. |
| 3 June 2011 | 72 | 44 | 21 | 7 | 1 | 73 | 1 | 1 | 3 | 150 | 0 | Independent MP Bob Katter (Kennedy, Qld) formed Katter's Australian Party. |
| 24 November 2011 | 72 | 44 | 20 | 7 | 1 | 72 | 1 | 1 | 4 | 150 | 0 | LNP MP Peter Slipper (Fisher, Qld) accepted Labor's nomination for the position of Speaker and resigned from the LNP. |
| 28 April 2012 | 71 | 44 | 20 | 7 | 1 | 72 | 1 | 1 | 5 | 150 | 0 | Labor MP Craig Thomson (Dobell, NSW) was suspended from the Labor Party due to an ongoing investigation involving his use of funds while a union official. |
Senate
| Party (no majority in this parliament) | Total | Vacant | Cause | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Labor | Coalition | Greens | DLP | Inds | ||||||||
| Liberal | LNP | Nationals | CLP | Total | ||||||||
| 1 July 2011 | 31 | 24 | 6 | 3 | 1 | 34 | 9 | 1 | 1 | 76 | 0 | |
| 22 August 2011 | 31 | 23 | 6 | 3 | 1 | 33 | 9 | 1 | 1 | 75 | 1 | Liberal senator Helen Coonan (NSW) resigned. |
| 1 July 2011 | 31 | 24 | 6 | 3 | 1 | 34 | 9 | 1 | 1 | 76 | 0 | Arthur Sinodinos (Liberal) was appointed to the New South Wales vacancy. |
| 27 February 2012 | 30 | 24 | 6 | 3 | 1 | 34 | 9 | 1 | 1 | 75 | 1 | Labor senator Mark Arbib (NSW) resigned. |
| 6 March 2012 | 31 | 24 | 6 | 3 | 1 | 34 | 9 | 1 | 1 | 76 | 0 | Bob Carr (Labor) was appointed to the New South Wales vacancy. |
| 31 March 2012 | 31 | 23 | 6 | 3 | 1 | 33 | 9 | 1 | 1 | 75 | 1 | Liberal senator Judith Adams (WA) died. |
| 2 May 2012 | 31 | 24 | 6 | 3 | 1 | 34 | 9 | 1 | 1 | 76 | 0 | Dean Smith (Liberal) was appointed to the Western Australia vacancy. |
| 1 June 2012 | 30 | 24 | 6 | 3 | 1 | 34 | 9 | 1 | 1 | 75 | 1 | Labor senator Nick Sherry (Tas) resigned. |
| 15 June 2012 | 30 | 24 | 6 | 3 | 1 | 34 | 8 | 1 | 1 | 74 | 2 | Greens senator Bob Brown (Tas) resigned. |
| 20 June 2012 | 31 | 24 | 6 | 3 | 1 | 34 | 9 | 1 | 1 | 76 | 0 | Lin Thorp (Labor) and Peter Whish-Wilson (Greens) were appointed to the Tasmanian vacancies. |
| 14 August 2012 | 31 | 23 | 6 | 3 | 1 | 33 | 9 | 1 | 1 | 75 | 1 | Liberal senator Mary Jo Fisher (SA) resigned. |
| 5 September 2012 | 31 | 24 | 6 | 3 | 1 | 34 | 9 | 1 | 1 | 76 | 0 | Anne Ruston (Liberal) was appointed to the South Australian vacancy. |
2016-present
editHouse of Representatives
| Party | Total | Vacant | Cause | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ALP | Coalition | Grn | NXT | KAP | Ind | |||||||
| Lib | LNP | Nat | Total | |||||||||
| 2 July 2016 | 69 | 45 | 21 | 10 | 76 | 1 | 1 | 1 | 2 | 150 | 0 | |
| 27 October 2017 | 69 | 45 | 21 | 9 | 75 | 1 | 1 | 1 | 2 | 149 | 1 | The High Court found Barnaby Joyce (Nat, New England, NSW) ineligible to be a member of parliament and declared his seat vacant. |
| 11 November 2017 | 69 | 44 | 21 | 9 | 74 | 1 | 1 | 1 | 2 | 148 | 2 | John Alexander (Lib, Bennelong, NSW) resigned over concerns he held British citizenship and was thus ineligible to be a member of parliament. |
| 2 December 2017 | 69 | 44 | 21 | 10 | 75 | 1 | 1 | 1 | 2 | 149 | 1 | Barnaby Joyce (Nat) was re-elected at the New England by-election. |
| 16 December 2017 | 69 | 45 | 21 | 10 | 76 | 1 | 1 | 1 | 2 | 150 | 0 | John Alexander (Lib) was re-elected at the Bennelong by-election. |
| 1 February 2018 | 68 | 45 | 21 | 10 | 76 | 1 | 1 | 1 | 2 | 149 | 1 | David Feeney (ALP, Batman, Vic) resigned over concerns that he held British citizenship, and was thus ineligible to be a member of parliament. |
Senate
| Party (no majority in this parliament) | Total | Vacant | Cause | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ALP | Coalition | Grn | PHON | NXT | LDP | DHJP | JLN | FFP | AC | Ind | ||||||||
| Lib | LNP | Nat | CLP | Total | ||||||||||||||
| 2 July 2016 | 26 | 21 | 5 | 3 | 1 | 30 | 9 | 4 | 3 | 1 | 1 | 1 | 1 | 0 | 76 | 0 | ||
| 30 September 2016 | 25 | 21 | 5 | 3 | 1 | 30 | 9 | 4 | 3 | 1 | 1 | 1 | 1 | 0 | 75 | 1 | Stephen Conroy (ALP, Vic) resigned. | |
| 25 October 2016 | 26 | 21 | 5 | 3 | 1 | 30 | 9 | 4 | 3 | 1 | 1 | 1 | 1 | 0 | 76 | 0 | Kimberley Kitching (ALP, Vic) was appointed to the Conroy vacancy. | |
| 1 November 2016 | 26 | 21 | 5 | 3 | 1 | 30 | 9 | 4 | 3 | 1 | 1 | 1 | 0 | 0 | 75 | 1 | Bob Day (FFP, SA) resigned. He was later found to have been ineligible by the High Court on 5 April 2017. | |
| 18 December 2016 | 26 | 21 | 5 | 3 | 1 | 30 | 9 | 3 | 3 | 1 | 1 | 1 | 0 | 1 | 75 | 1 | Rod Culleton (PHON, WA) resigned from One Nation to sit as an independent. | |
| 11 January 2017 | 26 | 21 | 5 | 3 | 1 | 30 | 9 | 3 | 3 | 1 | 1 | 1 | 0 | 0 | 74 | 2 | Rod Culleton (Ind, WA) was declared bankrupt and thus disqualified from being a senator. He was later ruled ineligible to have been elected. | |
| 7 February 2017 | 26 | 20 | 5 | 3 | 1 | 29 | 9 | 3 | 3 | 1 | 1 | 1 | 0 | 1 | 0 | 74 | 2 | Cory Bernardi (Lib, SA) resigned from the Liberal Party to form the Australian Conservatives. |
| 10 March 2017 | 26 | 20 | 5 | 3 | 1 | 29 | 9 | 4 | 3 | 1 | 1 | 1 | 0 | 1 | 0 | 75 | 1 | Peter Georgiou (PHON, WA) was elected at a recount to fill Culleton's vacancy. |
| 19 April 2017 | 26 | 20 | 5 | 3 | 1 | 29 | 9 | 4 | 3 | 1 | 1 | 1 | 1 | 1 | 0 | 76 | 0 | Lucy Gichuhi (FFP, SA) was elected at a recount to fill Day's vacancy. |
| 26 April 2017 | 26 | 20 | 5 | 3 | 1 | 29 | 9 | 4 | 3 | 1 | 1 | 1 | 1 | 1 | 76 | 0 | Family First merged into the Australian Conservatives, but Lucy Gichuhi (FFP, SA) elected to sit as an independent. | |
| 14 July 2017 | 26 | 20 | 5 | 3 | 1 | 29 | 8 | 4 | 3 | 1 | 1 | 1 | 1 | 1 | 75 | 1 | Scott Ludlam (Grn, WA) resigned having discovered he held New Zealand citizenship. | |
| 18 July 2017 | 26 | 20 | 5 | 3 | 1 | 29 | 7 | 4 | 3 | 1 | 1 | 1 | 1 | 1 | 74 | 2 | Larissa Waters (Grn, Qld) resigned having discovered she held Canadian citizenship. | |
| 31 July 2017 | 26 | 19 | 5 | 3 | 1 | 28 | 7 | 4 | 3 | 1 | 1 | 1 | 1 | 1 | 73 | 3 | Chris Back (Lib, WA) resigned. | |
| 16 August 2017 | 26 | 20 | 5 | 3 | 1 | 29 | 7 | 4 | 3 | 1 | 1 | 1 | 1 | 1 | 74 | 2 | Slade Brockman (Lib, WA) filled the Back vacancy. | |
| 27 October 2017 | 26 | 20 | 5 | 2 | 1 | 28 | 7 | 3 | 3 | 1 | 1 | 1 | 1 | 1 | 72 | 4 | The High Court ruled that, in addition to Ludlam and Waters, Fiona Nash (Nat, NSW) and Malcolm Roberts (PHON, Qld) were also ineligible. | |
| 31 October 2017 | 26 | 20 | 5 | 2 | 1 | 28 | 7 | 3 | 2 | 1 | 1 | 1 | 1 | 1 | 71 | 5 | Nick Xenophon (NXT, SA) resigned. | |
| 2 November 2017 | 26 | 19 | 5 | 2 | 1 | 27 | 7 | 3 | 2 | 1 | 1 | 1 | 1 | 1 | 70 | 6 | Stephen Parry (Lib, Tas) resigned having discovered that he held British citizenship. | |
| 10 November 2017 | 26 | 19 | 5 | 2 | 1 | 27 | 9 | 4 | 2 | 1 | 1 | 1 | 1 | 1 | 73 | 3 | Jordon Steele-John (Grn, WA), Andrew Bartlett (Grn, Qld) and Fraser Anning (PHON, Qld) were elected in countbacks to fill the Ludlam, Waters and Roberts vacancies. | |
| 14 November 2017 | 26 | 19 | 5 | 2 | 1 | 27 | 9 | 4 | 3 | 1 | 1 | 0 | 1 | 1 | 73 | 3 | Rex Patrick (NXT, SA) was appointed to the Xenophon vacancy. Meanwhile, Jacqui Lambie (JLN, Tas) resigned after discovering she held British citizenship. | |
| 22 November 2017 | 26 | 19 | 5 | 2 | 1 | 27 | 9 | 4 | 2 | 1 | 1 | 0 | 1 | 1 | 72 | 4 | Skye Kakoschke-Moore (NXT, SA) resigned after discovering she held British citizenship. | |
| 22 December 2017 | 26 | 20 | 5 | 2 | 1 | 28 | 9 | 4 | 2 | 1 | 1 | 0 | 1 | 1 | 73 | 3 | Liberal Jim Molan (NSW) was elected in a countback to fill the Nash vacancy. | |
| 15 January 2018 | 26 | 20 | 5 | 2 | 1 | 28 | 9 | 3 | 2 | 1 | 1 | 0 | 1 | 2 | 73 | 3 | Fraser Anning (PHON, Qld) formally left One Nation to sit as an independent. | |
| 25 January 2018 | 25 | 20 | 5 | 2 | 1 | 28 | 9 | 3 | 2 | 1 | 1 | 0 | 1 | 2 | 72 | 4 | Sam Dastyari (ALP, NSW) resigned. | |
| 2 February 2018 | 25 | 21 | 5 | 2 | 1 | 29 | 9 | 3 | 2 | 1 | 1 | 0 | 1 | 1 | 72 | 4 | Lucy Gichuhi (Ind, SA) joined the Liberal Party. | |