Aorangi School in Christchurch intends to mount a legal challenge against a decision by Education Minister Anne Tolley to close it.
Wednesday is the deadline for the school to respond.
On Tuesday, Mrs Tolley told Parliament the estimated net saving of closing, as opposed to rebuilding Aorangi, was almost $1.5 million and there were four other schools in the area nearby.
Aorangi's principal Stephanie Thompson disputes the minister's figures.
She told Morning Report she hopes the school's submission will convince the minister there are a range of problems with the closure, including a lack of capacity at nearby schools who would have to take Aorangi's pupils.
She said the submission will show the roll is not closing and the only way to make money from the closure is to sell the site, which National promised not to do in its first term in Government.