Stats NZ officials have labelled the latest Census as one with "good lessons learned" after announcing they won't prosecute those who didn't fill out their census forms due to an error.

The Government Agency is following legal advice after realising they hadn't met all the requirements of the Data and Statistics Act during the 2023 Census. 

It means those who didn't fill out their forms will no longer be charged a $2,000 fine for failing to comply. 

Deputy Government Statistician Simon Mason told Mike Hosking Breakfast there were three elements of the Act that weren't "completely followed". 

"We did partially do some of those things, we referred to the Act but not the specific clause," said Mason. 

"So based on advice we didn't feel it was right to force the prosecution through the courts and we won't be prosecuting as a result."

The agency said it generally prosecutes up to 60 people for refusing to take part, encouraging others to do the same, or threatening census staff. 

Mason said the threat of prosecution will garner roughly 5 per cent of the Census response. 

"It does trigger people to think about if they're responding or not," he said. 

In this case, Mason said the mistakes will be important to reflect on to prevent them from repeating in the next Census, reviews will be undertaken to determine what went wrong. 

"We find through every Census there's good lessons learned and those will come through various reviews, including external reviews we've undertaken as well."