General manager of Social and Population Insights at Stats NZ, Jason Attewell, told Morning Report that the way society is changing means it's timely to include the subject.
"In 2018 we didn't have questions on sex, gender and sexual identity so that didn't work really well for the rainbow community.
"So we're trying to do right now. We're doing these questions because they're so important; we need to reflect New Zealand and make the census inclusive for everyone really."
There would be questions on a person's sex at birth, gender identity and sexual identity.
The phrasing is still being refined and organisers have been liaising with the rainbow community to ensure the wording reflects its diversity, Attewell said.
However, the questions were already being used in other household surveys, such as the household economic survey, and they were working really well.
"In the previous census where we just had 'are you male or female' that's neither sex nor gender so we're really trying to get this right."
It was important to reflect Aotearoa and in past times it had been "a horrible experience" for the rainbow community not to see themselves in the data.
"The other thing is that these groups do have challenges that need to be addressed."
In the general social survey on wellbeing, there was a question on sexual identity and it was found that some groups in the rainbow community had worse wellbeing outcomes, so their overall quality of life was worse and they weren't able to express themselves.
While Stats NZ does not draw up policy, it gathers data that can help policy makers, Attewell said. One area this could be useful is with funding issues, such as gender reassignment surgery for trans people.
"The beauty of the census is that it touches all New Zealanders so this is really our only chance to be able to get an idea of the scale of the rainbow community."
- RNZ