He also faced further charges over possessing objectionable material.
Michael Beaumont was sentenced today in North Shore District Court.
The 72-year-old pleaded guilty to charges of indecently assaulting two 12-year-old girls and one 9-year-old girl in 1977.
He did so just moments prior to standing trial in February.
Judge Jonathan Down has also ordered Beaumont to be registered as a child sex offender.
The sentence includes 11 months for the three indecent assaults, and one month for possessing objectionable material.
Beaumont's charge of possessing objectionable material was a centre of debate at sentencing.
The material was literature depicting sexual violations against children.
Crown lawyer Nick Webby said it undermined the previous argument that Beaumont had not offended since the 1970s.
"There has not been 40 years when the offender has stayed out of the police's attention."
Webby said although it was literature, the acts depicted were at the most serious end of the spectrum.
But Beaumont's lawyer James Olsen argued it shouldn't land him on the register.
"Certainly if there had been some other contact with a child, that would be a real concern," Olsen said.
"But in terms of just possessing the material alone... there are no victims."
In delivering the sentence, Judge Down concluded he could pose a continued risk to children in the community.
"The further offending demonstrates that your perverse thinking is still in place and requires further assessment."
One of the victims - who has name suppression and is 50 years old now - has read out her victim impact statement in court.
"As my family sat in a circle and prayed the rosary, respectfully with closed eyes, I sat beside Brother Michael," she said.
She was initially excited that a man of God wanted to sit beside her, but that quickly changed once the abuse started.
"In trying to process this abuse I concluded I was a naughty child before God, I had sinned."
She said despite her love for the church as a child, the abuse made it hard to continue living as a practising catholic, and she eventually left.
"Every time I went to church I was taunted by images of the clergy. Church became a place of trauma."
"I walked away in anger and shame, as my decision to leave also meant my children couldn't go to mass."
Judge Down said in sentencing the victim has been robbed of a form of support and comfort through the church.
"I can understand how she feels, I'm a person of faith myself and where someone abuses that trust... it can have all kinds of ramifications on ... how they turn to the church for support."
He was last year listed under administration support for tertiary education provider The Catholic Institute of New Zealand on its website.
"Michael was a teacher for many years and is now working part time for TCI in a support role and part time for the Auckland Diocese in a similar role for the RE [religious education] Team," it said.
"He has also, since its inception, been involved as a member of the team fielding calls to the Family Violence Information Line, part of the "It's not OK" campaign helping to increase awareness around family violence and abuse."
Beaumont also formerly worked part-time for the Auckland Catholic Diocese.
