The former Chief Technology Officer for the Department of Defence has left his post, moving to a role as Chief Information Officer of the Department of Immigration and Citizenship.

One-time Defence CTO Matthew Yannopolous is now the country’s CIO for immigration. Mr Yannopolous will reportedly being working in the role from September.

Yannopolous will take over from current CIO Tony Kwan, who has been in the chair since 2011, following a long stint as CIO of the Australian Government's former Department of Education, Science and Training (now known as the Department of Education, Employment and Workplace Relations).

During his time as Defence CTO, Yannopolous designed and planned the technological world of one of Australia's biggest spenders, with an annual IT budget of around $1.3 billion.

Yannopolous brought about projects such as the centralised processing project worth around $800 million, and a $100 million next-generation desktop upgrade.

The former defence CTO also championed the data centre migration project, allowing the military services to store masses of confidential information gathered from a variety of technological and international sources in one handy location.

Yannopolous’ former position will be temporarily taken by Major General Michael Milford but will be advertised again shortly, the Department said.