National's then finance spokeswoman Amy Adams said the question did not go to the core business of the IRD and requested that the SSC conduct a formal investigation.
The investigation into the survey was released today and concluded although the question was not politically motivated and was an isolated incident, it was disappointing that the question was asked.
"I'm disappointed this has happened," SSC Deputy Commissioner John Ombler said.
"It is never okay for a government agency to seek or collect information on the political leanings or party affiliations of citizens."
He said the questions asked were "ill-judged, inappropriate and had the potential to undermine the principle of political neutrality".
Ombler said it was also disappointing political neutrality was not at the front and centre of the work and thinking behind these surveys.
"Someone should have asked the question."
The questions, he said, were motivated by "academic rigour" such as the IRD wanting to better understand the tax system and the Department of Conservation wanting to have a better grasp of people's thoughts on pest control.
It also helped Stats NZ to develop an effective marketing campaign for the 2018 Census, Ombler said.
"I don't doubt research on these surveys shows the results might be more meaningful in a broad sense if questions of a political nature are included.
"But this cannot be at the expense of political neutrality, which is the overriding consideration in the Public Service."
Ombler said the incident should serve as a timely wake-up call.
The SSC has asked all public service chief executives to ensure all public surveys undergo a specific check for political neutrality.
He also wrote to the Public Service functional lead on data, Liz McPherson, and asked her to work to help ensure any issues around political neutrality is well understood across government.
