The Westmeath car components firm IRALCO has told employees that the factory will be shut down from 12 December until 12 January.
The downturn in new car sales on the country's forecourts has been blamed for the decision to send 300 workers at the factory home from work for a month.
It is understood workers had expected to be told to take two weeks of their annual leave over Christmas.
However, management have now said that all staff will be out of work for another two weeks without pay.
IRALCO was taken over by new management during the summer when it ran into financial difficulty.
100 workers in the factory have lost their jobs since July.
The firm makes trim and other components for Volvo and Volkswagen cars.
IRALCO Managing Director Tom Hyland said all of the firm's customers were closing down their operations for Christmas.
'We don't have any demand and we're just mirroring what our customers are doing, there's effectively no choice in that respect,' he added.
