Braddan commissioners say they expect the Roundhouse to lose more than £1 million in the next six months.
A report to the local authority at its June meeting said its expected income from the facility's rents and sports hall would be £355,000.
However, salaries, capital costs and other costs would amount to £1.34 million.
It also estimated it had lost £64,000 in five months because of unsigned tenancy agreements.
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