The Deputy Chief Minister of the Australian Capital Territory is the second-most senior officer in the government of the Australian Capital Territory. The position has been a ministerial portfolio since its establishment in 1989. Unlike in other states and territories, the deputy chief minister of the ACT is not nominally appointed by an administrator or vice-regal, but by the chief minister.
The current deputy chief minister is the Labor Party's Yvette Berry who took over from former Labor deputy leader Simon Corbell on 31 October 2016, following Corbell's retirement at the 2016 Australian Capital Territory election.
The 1989 ACT election, which was the first under self-government, resulted in Labor emerging as the largest party in the Legislative Assembly with five seats. Following the formation of the inaugural government ministry under chief minister Rosemary Follett, deputy Labor leader Paul Whalan was appointed to the position.
When a no-confidence motion resulted in the end of the Follett government, new chief minister and Liberal Party leader Trevor Kaine briefly held all portfolios after becoming chief minister, before the new ministry was sworn in on 13 December 1988.
There was no deputy chief minister between 29 May 1991 and 18 June 1991 after Kaine sacked the Residents Rally (including its leader, deputy chief minister Bernard Collaery) from the Alliance government. Independents Group leader Craig Duby expected to be elevated to the position, but this never occurred.
Gary Humphries, Katy Gallagher and Andrew Barr are the only deputy chief ministers who have gone on to become chief minister. Trevor Kaine is the only chief minister who has taken a 'backward' step to become deputy chief minister.
The duties of the deputy chief minister are to act on behalf of the chief minister of the Australian Capital Territory in his or her absence overseas or on leave. The deputy chief minister has always been a member of the Cabinet, and has always held at least one substantive portfolio (it would be technically possible for a minister to hold only the portfolio of deputy chief minister, but this has never happened).
If the chief minister were to die, become incapacitated or resign, the Assembly would normally elect the deputy chief minister as chief minister. If the governing or majority party had not yet elected a new leader, that appointment would be on an interim basis. Should a different leader emerge, that person would then be appointed chief minister.