Government chief operating officer Stephen Kelly is to leave Whitehall to join business software firm Sage as group executive.
The COO announced his resignation today, but will not leave the public sector "for a few months", according to his colleague and head of the Government Digital Service (GDS), Mike Bracken, joining Sage in November.
Bracken paid tribute to Kelly in a blog post, and wrote: "I doubt Stephen will miss the parochial nature of Whitehall, but I hope he reflects that he has played a huge part in delivering the early stages of the UK Government’s digital development."
Kelly joined as COO back in September 2012, tasked with smoothing the path for the Government’s digital transformation programme as it tries to drive efficiency and cut costs.
He took many Cabinet Office functions into the Efficency and Reform Group, helping identify £14.3bn savings over 2013/14.
Cabinet Office minister Francis Maude called Kelly a "terrific leader".
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."
Sage is third-largest ERP provider behind Oracle and SAP, targeting the mid-market and counting millions of customers.
The Cabinet Office were unavailable for comment at the time of writing.