Worksafe has told Te Aroha College it has breached health and safety laws and failed to prevent "psychosocial risk" to its staff.
The Waikato school has been told it must take measures to deal with those issues by December 2.
The school has also taken the unusual step of apologising publicly in its newsletter to two teachers for any distress caused by false rumours that they had faked permission slips.
The Government's health and safety watchdog launched an inquiry at the Waikato school earlier this year after receiving a complaint about staff wellbeing.
It has since received at least nine other complaints on similar lines.
• Worksafe making inquiries over staff wellbeing at Te Aroha College
• New worksafe complaints laid against Te Aroha College over staff wellbeing
• St Peter's School: Worksafe says bullying concerns have been addressed
• Covid 19 outbreak: Teachers juggling online classes and homelife the real heroes
A Worksafe inspector has since issued the school an improvement notice warning it is contravening the Health and Safety at Work Act.
It said Worksafe had "concluded from inquiries that Te Aroha College has not effectively managed psychosocial risk to workers in the workplace".
By December 2 the school must comply with the notice, which requires it to complete a risk assessment and put in place a system to deal with psychosocial risks to workers.
New chair Debbie Burge confirmed to the Herald that the college was on track to fulfil those requirements.
A Worksafe spokesperson told the Herald the compliance period for improvement notices could be extended if an organisation had a good reason for needing more time.
"WorkSafe's process with Te Aroha College is ongoing. Complying with the direction of the improvement notice may not end WorkSafe's involvement, but that is a decision which will be made by the appropriate staff within WorkSafe at the time," they said.
The small Waikato school has also apologised in its public November newsletter for any distress caused by rumours that two teachers had faked permission slips and other documents.
It's not clear who started the rumours.
Its November newsletter said the two named teachers were resigning at the end of January 2022.
"We have been advised of rumours circulating that [the teachers] have not acted professionally and have falsified documents and permission slips," the newsletter read.
"There is no substance to these rumours. The Board regrets any distress caused to [the teachers] by these rumours."
It also acknowledged the pair's years of service to the community and wished them all the best for the future.
Asked whether Worksafe or another body had required that notice to be put in the newsletter, Burge said she was unable to comment due to the Privacy Act.
The school board's previous chair Teena Cornes resigned after Worksafe began its inquiries earlier this year, and in October the board requested formal support from the Ministry of Education.
The November newsletter said that Ted Benton had been appointed as limited statutory manager, responsible for policy and employment. He was also helping with governance processes and procedures.
"We believe his expert skills will enable us to quickly review and strengthen areas of our governance that are not performing as effectively as they could be," the newsletter said.
The school's principal Heather Gorrie, the leadership team and staff would continue to "ensure the school's focus is on our students, and teaching, learning and achievement", it said.