The move will save Cambridgeshire County Council almost £3.6m over the next four years on the cost of providing these services.
The two councils launched the system in October last year to share business services such as HR, legal services, internal audit and finance. To date the shared service has banked £11m of savings for the two authorities.
This latest move builds on the strengths of LGSS who already provide
Northamptonshire County Council with the lowest cost IT services per user of any UK county council.
It is hoped the savings will be made through a combination of standardising processes, sharing systems and technologies, merging and rationalising the teams from both authorities, reducing management overheads and improving productivity.
Leader of Cambridgeshire County Council, Cllr Nick Clarke said: "We have shown how successful sharing services can be with our other back office services and the transfer of IT and facilities management to LGSS was the next logical step. By making further savings from our business support services we can ensure that the vast majority of our money goes directly to the front line."
"This is just the beginning for LGSS. We have proved the case for sharing services and are now looking for other public sector organisations that we can work with to reduce the cost of these services even further."