Grant Thornton plans to offer unlimited vacation days in U.S.

Grant Thornton, the sixth-largest U.S. accounting firm, will offer U.S. employees unlimited time off, a strategy it hopes will entice workers from rivals with traditional vacation plans.

The new policy, in place by November, will affect 6,700 workers and replace vacation time that capped days off at 30 for the most senior staff, the firm said. Less than 1 percent of U.S. companies offer unlimited vacation, according to 2015 data from the Society of Human Resource Management. Netflix Inc. Virgin Group Ltd. and General Electric Co. have made the switch for some employees in the last few years.

"This is a modern move for an industry where these types of benefits aren't really common," said Pamela Harless, chief people and culture officer for Grant Thornton. "We are convinced it will help us to be far more attractive in retaining talent as well as attracting talent."

U.S. companies, feeling the pressure to hang on to their best workers in an improving economy, are adding benefits with particular appeal to the Millennial generation, workers now in their 20s and early 30s. They've been regularly announcing more paid leave for new mothers and fathers, insurance coverage for same-sex partners and flexible time arrangements that range from working remotely to as much time off as a worker wants. The U.S. unemployment rate fell to 5.1 percent in August, the lowest since 2008.

Grant Thornton has been working for the last 18 months to emphasize personal responsibility as part of its culture, Harless said. In December, the Chicago-based company added bonus days off ahead of a busy season from January through May, she said. After the U.S. tax season, employees created their own, more flexible schedules. Removing the limit on vacation days was the next step, Harless said.

Among the so-called Big 4 accounting firms, KPMG LLP offers a maximum of 30 days, Deloitte LLP has a maximum 35 days and PwC has a maximum of 22 for management level staff, according to the companies. EY has a minimum of 15 days with additional days added with years of service, according to a description of the policy on the company website.

The shift to potentially unlimited paid time hasn't worked for everyone. Crowdfunding platform Kickstarter, for instance, recently ended a flexible policy in favor of a fixed maximum of 25 days, according to Justin Kazmark, a spokesman, without providing further details.

Employees with a fixed number of vacations days are more likely to take them, said Kenneth Matos, senior director of research at the Families and Work Institute, "When there's no limit, there isn't the same push to take the days." That results in some employees taking less time off, he said.

Almost all U.S. companies offer some form of paid time off, at least for full-time workers, Matos said. The average number of paid days off at U.S. companies was 16 in 2013, the most recent year data was collected, according to the Alexandria, Virginia-based SHRM. About half of employees use up all of their available days, and 15 percent don't take any, according to a survey by job search website Glassdoor Inc. of 2,002 adults last year.

Grant Thornton will be measuring the program and making sure that employees are using vacation time, Harless said. "We are very confident that we are the right type of culture and the right type of environment where this can make a huge difference for our people and for our clients," she said.