A former staff member in the office of Education Minister Hekia Parata is pursuing a personal grievance against ministerial services.
Ministerial Services confirmed a staff member who worked in Ms Parata's office had lodged a personal grievance against ministerial services, which is part of the Department of Internal Affairs.
It would not release the details of the case in order to protect the privacy of the individual.
The information was obtained by Green party co-leader Metiria Turei under the Official Information Act.
"Hekia is unable to manage her office well - it's costing the public as a result," Ms Turei said.
"This is another employment issue on top of a number, there seems to be a pattern in Hekia Parata's office of a poor working environment, and poor working environments."
Ms Turei said Ms Parata wasn't fit to be a minister and should resign.
The case could end in another bill for taxpayers after the $425,000 paid out to Education Secretary Lesley Longstone.
Last year Ms Longstone resigned as Education Secretary, receiving a before-tax payout of $267,953 severance pay and $157,523 in outstanding holiday pay and a payment in lieu of notice. She and Ms Parata were said to have had a tense working relationship.
Ms Longstone was recruited from the UK and quit as the Education Ministry's top official after just 13 months in the job.
Radio New Zealand reported a senior private secretary left the minister's office in December last year at the same time Ms Longstone departed and three other private secretaries had also left the office.
It was unclear on what grounds these staff left her office.
Information received under the Official Information Act showed between 2008 and 2012, two people left Ms Parata's ministerial office.
Since that OIA request Ms Parata has had four staff leave her ministerial office between December last year and March this year.
Between 2008 and 2012, eight people left Prime Minister John Key's ministerial office.