Southeastern Container says it plans to close its Beloit plant by May.
The plastic bottle manufacturing plant employs about 50 people.
The Beloit Daily News reported that a letter to employees Thursday says production is being moved to facilities in either Bowling Green, Ohio or Effingham, Ill.
Workers will be offered the opportunity to transfer to these locations, but only 10 positions will be available in Effingham and eight will be available in Bowling Green. Workers also would be eligible for severance pay if they did not seek a transfer.
The 244,000-square-foot plant opened in Beloit in 2007.