In the South Australian public service, Grimes obtained the role of Deputy Under Secretary in the Department of Treasury and Finance.[3]
Between March 2005 and January 2007, Grimes was ACT Under Treasurer in the ACT Public Service.[4] In the role he oversaw the ACT Government's transition to the GFS accounting system, a change that then Treasurer Jon Stanhope suggested would enable the Government to have a more realistic and less volatile basis upon which to base budgeting decisions. He also assisted in developing and delivering the 2006–07 ACT Government Budget, which involved major structural change to ACT Government agencies; and consolidated IT and procurement services across the ACT public service.[4]
Grimes was appointed Acting Secretary of the Department of Sustainability, Environment, Water, Population and Communities in September 2010,[6] moving into the role formally in 2011.[7][8] His responsibilities at the Department included matters related to environment protection and conservation of biodiversity, air quality, national fuel quality standards and administration of the Australian Antarctic Territory.[9]
In September 2013, after the Abbott government was sworn in, Grimes was transferred to head the Department of Agriculture.[10][11] In the role, Grimes was responsible for matters including the agricultural, pastoral, fishing, food and forest industries, rural adjustment and drought issues, food security policy and programs, and quarantine.[12]
In March 2015, Agriculture Minister Barnaby Joyce announced Grimes would be stepping down from his Secretary position,[13][14] with media reporting that Joyce and Grimes were understood to have different philosophical views on environmental issues.[15] Grimes reportedly wrote that he "agreed that the minister would be better supported... by a new secretary with a different background and set of policy skills."[16]
Grimes was appointed Commissioner of the Victorian Public Sector Commission in December 2017. His term begins on 22 January 2018. He left the role in January 2020 in order to be closer to his family in Canberra.[17]
In June 2010, Grimes was awarded a Public Service Medal for outstanding public service in the development of the Australian Government's response to the global financial crisis.[22]
^Department of Sustainability, Environment, Water, Population and Communities (2011), Annual Report 2010–2011(PDF), Australian Government, p. 13, archived from the original(PDF) on 11 March 2014{{citation}}: CS1 maint: multiple names: authors list (link)
^ abJon Stanhope, Ginninderra-Chief Minister, Treasurer, Minister for Business and Economic Development, Minister for Indigenous Affairs and Minister for the Arts (13 December 2006). "Dr Paul Grimes". Parliamentary Debates (Hansard). ACT Government: ACT Legislative Assembly. p. 4127. Archived from the original on 3 April 2011.