The Internal Revenue Service is asking Congress to clarify that personal use of mobile phones provided by employers won't be taxed.

A tax law on the books for many years technically required that personal use of employer-provided mobile phones be subject to taxes, but few employers tracked personal use of mobile phones and the IRS rarely enforced the provision.

Now, IRS Commissioner Doug Shulman is asking Congress to draft new legislation, arguing that current law is "burdensome, poorly understood by taxpayers, and difficult for the IRS to administer consistently.”

“Treasury Secretary Geithner and I ask that Congress act to make clear that there will be no tax consequence to employers or employees for personal use of work-related devices such as cell phones provided by employers,” Shulman says. “The passage of time, advances in technology, and the nature of communication in the modern workplace have rendered this law obsolete.”