Privacy Commissioner Marie Shroff has confirmed she will investigate Social Development Minister Paula Bennett after the release of details of two mothers' income.
Last month, Ms Bennett released the income details of solo mothers Natasha Fuller and Jennifer Johnston, who publicly criticised cuts to the Training Incentive Allowance (TIA).
At the time it was reported a complaint had been laid with the Office of the Privacy Commissioner.
Today, Ms Shroff confirmed she had received a complaint.
Her office would decide whether it needed further information and then "consider the possible issues involved" before asking Ms Bennett to explain her side of the story.
"The Privacy Act requires us to conduct our investigations with the complainant and respondent in a confidential manner.
"A good number of complaints to my office are resolved by a settlement between the parties."
The rest were resolved by a final opinion from the commissioner, she said.