Census 2013 general manager Sarah Minson said SNZ continued to encourage people to complete their forms if the did not do so on Census night - March 5, 2013.
Since Census night, SNZ had done everything possible to encourage people to participate but, as a last resort, might prosecute people who refuse to fill in their forms or provide false information, she said.
"When deciding to prosecute someone for not completing their census form we use the following criteria ... Whether an offence has been committed; whether there is sufficient legally admissible evidence to prove the charge beyond reasonable doubt; the seriousness of the offence and the personal circumstances of the individual."
Hastings man Thomas Martin escaped a fine when he filled the forms in at his District Court appearance last December.
Outside court Martin said he had decided to plead guilty to the charge and fill in the forms after getting legal advice.
Judge Bridget MacIntosh convicted and discharged him.
But he still disagreed with being forced to fill in the census.
In 2006, after the previous Census, SNZ prosecuted 72 people, resulting in 41 convictions.
By the numbers:
* 99 cases have been filed in the District Courts and pre-hearings arranged for them;
* SNZ has been unable to issue a summons for five people;
* 10 people have been confirmed as Gone No Address so their charges have been withdrawn;
* 22 defendants have completed their forms and the charges against these have been withdrawn prior to going to court;
* 23 defendants have been convicted and fined between $50 -200 per charge;
* 11 defendants have pleaded not guilty; and
* 28 were either still yet to appear or had appeared but SNZ had not been notified about the outcome.
By the region:
Auckland 8
Blenheim 3
Christchurch 15
Greymouth 1
Hamilton 5
Hastings 1
Huntly 2
Hutt Valley 2
Invercargill 1
Kaikohe 11
Manukau 2
Marton/Wanganui 1
Masterton 1
Morrinsville 4
Nelson 2
New Plymouth 1
North Shore 2
Palmerston North 2
Papakura 3
Porirua 2
Pukekohe 2
Rangiora 2
Ruatoria 2
Tauranga 2
Thames 3
Timaru / Oamaru 1
Waihi 1
Waitakere 4
Wellington 4
Westport 1
Whangarei 8
- additional reporting Northland Advocate and Hawke's Bay Today