Today's policy is similar to one announced by Act leader David Seymour earlier this year, which would cut jail time if certain prisoners complete literacy, numeracy and driver licensing courses.
Tougher sentencing and bail conditions means the Government's books will be hit by an extra $2.5 billion over about five years as it builds new prisons and keeps more New Zealanders locked up.
Upston said rehabilitation programmes work and National wanted more prisoners to complete them.
"We will invest an extra $48 million in rehabilitation and reintegration programmes over the next four years to deliver another 6000 places. That's on top of National's major investment in rehabilitation, which has seen the number of offenders in training or treatment programmes almost triple since 2008."