About 85% of KPMG's 11,000 staff have volunteered to move to a four-day week or take a partially-paid career break if such steps become necessary to prevent redundancies during the recession.
The voluntary career breaks will last between four and 12 weeks on 30% of pay. Staff were asked to submit a voluntary application for these arrangements in January.
If a department at the firm needs to take action to avoid redundancies, it will ask employees who have signed up to adopt the revised working practices, known as flexible futures. The changes can be initiated at any point up to the end of September 2010 and staff that have indicated they want to take part will serve a notice period before the arrangements become effective. One-week's notice will be served by staff taking reduced hours and one-month notice is required for career breaks.
Ingrid Waterfield, UK head of reward at KPMG, said: "We want to keep our top talent and this is a way of retaining people rather than having to go down the redundancy route."