Staff at Aspire Academy in Harlow will vote on industrial action over concerns for their health and safety, it has been announced this morning.
The school for students outside mainstream education is part of the TBAP multi-academy trust, and was the subject of a BBC Panorama investigation in March after the head teacher blew the whistle on serious financial trouble.
Earlier this month, students in years 7, 8 and 9 were sent home because of unsafe staffing levels.
UNISON, which represents support staff at Aspire, says it has been raising concerns about the finances and staffing levels since early 2018, shortly after TBAP took over the school.
They say that many staff, including the head teacher, are off sick because of the problems at the school.
Support staff have already supported industrial action in a recent consultative ballot.
UNISON Eastern regional manager Tim Roberts said:
"It's hard to see how the school can continue to operate in this environment. TBAP must act quickly to get a grip on the increasingly unsafe situation it's created at Aspire or deal with the consequences."
The ballot on industrial action will close in June.
In 2018 TBAP, the multi academy trust that Aspire Academy is part of, was issued with a financial notice to improve by the Education and Schools Funding Agency.
A spokesperson for the TBAP Multi Academy Trust said in a statement: "The TBAP Multi Academy Trust provides proven, outstanding alternative education and intervention for the most vulnerable learners in our society.
The Trust is aware of the possibility of industrial action at Aspire Academy. Regular meetings with union representatives are taking place with a view to resolving the issues that have been raised.
The Trust adheres to the very highest standards in maintaining a safe environment for all."