Tuition reimbursement has long been a benefit of corporate employers. And it’s no wonder. Companies see it as a way to retain current workers, keep employees’ skills up-to-speed, and attract new talent. About five in six—or 83%—of organizations surveyed by the International Foundation of Employee Benefit Plans last year offered some sort of educational assistance or tuition reimbursement to their employees.
While there’s no doubt all employees would appreciate help paying for school, the benefit is especially popular among the fastest growing segment of the workforce—millennials. A 2015 survey by EdAssist, a company that advises employers on their tuition assistance programs, found that if asked to choose between similar jobs, nearly 60% of respondents would pick the job with strong potential for professional development over one with regular pay raises. One in two millennials said they expected an employer’s financial support in paying for further education.
Despite the near-universal appeal of education assistance, just how much help a worker can get from his employer is often limited by—of all things—the United States tax code. The Internal Revenue Service effectively caps the tax-free tuition benefits an employee can receive per year at $5,250—enough for maybe a course or two. Anything over that counts as compensation and the employee incurs taxes accordingly, unless an employee could otherwise count it as a business expense.
The rule makes the unlimited tuition reimbursement offered by the following six employers on Fortune’s Best Companies to Work For list especially rare. Sure, employees at these companies might have to pay taxes on any educational assistance over the IRS’s threshold, but it still beats paying for school all by yourself.
Acuity
Rank: 2
Industry: Financial Services and Insurance
Headquarters: Sheboygan, Wisconsin
Full Time Employees: 1,157
Acuity says that 11.8%—or 132—employees took part in the tuition assistance program last year. The company as a whole paid $98,697 in reimbursements.
Boston Consulting Group
Rank: 3
Industry: Professional Services
Headquarters: Boston
Full Time Employees: 2,943
BCG said that nearly 10% of its employees took advantage of educational assistance last year; it wouldn't disclose how much it spent on the program.
Burns & McDonnell
Rank: 16
Industry: Engineering
Headquarters: Kansas City, Missouri
Full Time Employees: 4,839
About 2.5% of Burns & McDonnells' employees—or 125 workers—cashed in on the benefit last year. As a result, the company paid $755,416 in tuition assistance. Over the last several years, the assistance program has cost the company an average of $650,000.
ARI
Rank: 24
Industry: Professional Services
Headquarters: Mt. Laurel, New Jersey
Full Time Employees: 1,431
About 9% of ARI's workers participated in the tuition assistance program last year, which cost the company more than $1 million.
EY
Rank: 49
Industry: Professional Services
Headquarters: New York
Full Time Employees: 35,138
EY said that job-related tuition reimbursement is approved and funded by its individual business units, so it could not track the program's overall use or cost.
TD Industries
Rank: 65
Industry: Construction and Real Estate
Headquarters: Dallas, Texas
Full Time Employees: 2,025
The company spent $1,020,150 on tuition and training reimbursements in 2015 as 92% of its employees took advantage of the benefit. That staggering participation rate is due to the characteristics of its workforce. Because TD Industries is a construction company, more of its employees enroll in classes for technical training—often at night—versus courses for college credit. It considers any cost associated with a class as "tuition."
See the full list of Fortune's 100 Best Companies to Work For at fortune.com/bestcompanies, where you can also find job searching tips, career advice, and secrets from recruiters.