Treasury documents show the school staffing ratios abandoned by the Government earlier this month were a watered down version of its original plan.
The documents, published on Friday, show the Government originally expected to cut 1300 teaching jobs from primary schools next year.
It wanted to increase the staffing ratio for new entrant classes from one to 15 to one to 18 and expected to save more than $90 million a year by 2016.
By Budget day on 24 May, the Government had decided to leave the new entrant ratio unchanged and had reduced its final saving estimate to $70 million a year.
Despite the changes, teachers and parents opposed the Government's plan and it dumped the policy just two weeks after Budget day.
Government warned education costs becoming unsustainable
Budget documents also show rising school rolls have prompted the Ministry of Education to warn the Government that education costs are becoming unsustainable.
The papers published on Friday say an increase in the number of school children will drive up staffing and property costs.
It says the change will not happen evenly, with Auckland expecting 60,000 more school children while most other areas will have fewer.
The ministry says schools will increasingly be in the wrong places and poorly matched to future requirements, with too many buildings that are old, leaky and earthquake prone.