The proportion of people quitting their jobs for new work elsewhere has risen from 4.6% last year to 7.1%, according to research by salary expert Computer Economics.
The upturn, the highest rate of job churn since the end of 2001, is leading employers to review salaries and working conditions.
"Companies need to think about training, making sure their benefits package is competitive. That is what retains people. It is not just money that makes people stay, it is technology and a good working environment," said Computer Economics' director Paul Campfield.
Annual salaries for IT staff are showing increases ranging from 3.7% to 4.1%, as companies keep a tight rein on their ITbudgets.
Bonuses have fallen from an average of 14.9% in 2004 to 13.1% in 2005 for managers, and from 8.0% to 7.6% for other IT staff. The research is based on data from 560 IT employers.
Traditional annual pay rises for staff are now a thing of the past, with most firms paying their IT staff according to results, said Computer Economics.
However, the upturn has caught many employers off guard, leaving them with key positions unfilled in their IT departments, recruitment companies report.
Employers who have neglected to manage their staff have been forced to make generous counter-offers to woo employees back after they have been offered jobs elsewhere, said Jake King, divisional director of recruitment firm Abraxas.
"People are resigning and then being offered a lot of money to stay. While that might be flattering for the individual, it is not indicative of a company that is managing its staff properly," he said.
Andrew Thomas, director at recruitment agency Volt, said companies were taking work/life balance issues and flexible working more seriously as a way of retaining good staff.
"The feedback we are getting is that job changing is not driven by salary, although it is important," he said.
"People expect to get a pay rise of sorts when they change jobs, but it is more about a feeling of worth. If there is a feeling of worth the employer manages to retain new staff."
In Volt's experience, most people who accept counter-offers to stay with their existing employers leave between four and six months later, because the employer has not addressed the underlying issues.