The Magic Circle firm has not made a final decision about the retention rate, and said the figure was a “working assumption in light of the current financial climate.”
Allen & Overy retained 86% of its trainees in 2008, 90% in 2007.
The firm offers its training contracts two years in advance, with some 50 trainees joining each year.
Allen & Overy is expected to cut 9% of associates, 9% of support staff and 9% of its partnership.
Around half of the affected positions are in London. The firm is also freezing pay and billing rates at 2008 levels.
Founded in 1930, Allen & Overy has approximately 5,500 staff and 31 offices worldwide.