UK government chief operating officer Stephen Kelly has resigned to join Sage as group chief executive. Kelly will remain a civil servant until joining the software house in November 2014.

The Newcastle-headquartered multinational is the third biggest ERP software provider in the world, behind SAP and Oracle. It has over six million customer worldwide and focuses on the SME market.

Kelly joined the Cabinet Office in 2011 and led the Efficiency and Reform Group (ERG), which works with HM Treasury and government departments to save money on the goods and services they buy, such as ICT.

He worked on an ongoing Cabinet Office project to encourage the growth of public sector mutuals, organisations that have left the public sector but continue to deliver public services.

Kelly was also responsible for driving the 'Next Generation Shared Services' strategy, which is now coming to fruition with two shared service centres being set up to process Whitehall's back office services such as IT, HR and finance.

The first centre, which provides back office services to the Department for Transport (DfT) and its agencies, is being run by business process outsourcing firm arvarto via a contract won in March 2013.

The second, run by a joint venture between the Cabinet Office and French IT multinational Steria, is delivering services to the Department for Work and Pensions (DWP), Defra and the Environment Agency. The contract was awarded in November last year. Both centres plan to expand to provide services to more departments.

Before joining the civil service, Kelly worked as an executive at Oracle for nine years, then as CEO at CRM specialist Chordiant for eight years. His last private sector role was as CEO of software firm Micro Focus.

Kelly said: "After immense consideration, I have decided to return to the private sector as Chief Executive of Sage. I have always been passionate about supporting SMEs, and this role is an excellent opportunity for me to play a crucial role in creating jobs and growth.

"Since joining the Civil Service, I have been exceedingly fortunate to work for a minister who demonstrates outstanding leadership, inspiration and clarity, and I have encountered exceptionally bright, talented and committed colleagues.

"I am extremely pleased with the achievements of the Efficiency and Reform Group and Cabinet Office teams in driving sustainable efficiency and reform and the resulting savings accrued."

Cabinet Office minister Francis Maude said: "Stephen Kelly has been a terrific leader of the government's efficiency and reform programme which for last year alone saved taxpayers £14.3 billion against a 2009-10 baseline. Getting more for less is a central part of our long-term plan for a stronger economy and I would like to thank Stephen for his energy, tenacity and commitment.

"Although we have achieved an enormous amount we are still at the start of our work to transform Whitehall. Stephen will be missed greatly but he has developed an exceptionally strong team who will continue our reform work including by further strengthening commercial skills, digitising government and ensuring our major projects run to time and budget."