The Department of Correction is cutting 130 jobs in a restructuring.
Chief executive Ray Smith says changes at the national office and some regional offices will save $10 million a year which will be put into other areas.
Slightly fewer positions are being lost than proposed in May, and Mr Smith says no front-line roles will be affected.
He says the restructuring will bring together three service arms: prisons, rehabilitation and probation.
Mr Smith says the departmental changes will allow Corrections to easily target the underlying causes of offending with the aim of reducing re-offending by 25% by 2017.
He says it has been a testing time for many staff and he thanks them for their patience and professionalism.
The prison officers union says its members will not be affected by the restructuring.
President of the Corrections Association, Beven Hanlon, says the changes will not affect a majority of its members.
He says only a select few in the union with secretary positions have suffered job losses.
Mr Hanlon says he supports the department's goal to reduce reoffending by 25% by 2017.
Corrections Minister Anne Tolley, meanwhile, says the people affected by the job cuts are all backroom staff.
Mrs Tolley says the department is doing its best to help find jobs for those who are being made redundant.