In an effort to cut back on driving and greenhouse emissions, companies with at least 20 employees will have to offer one of three options to all who work at least 10 hours a week, effective in late December.

One proposal calls for the company to set up a program under which employees can make pretax contributions to the federal legal limit of $115 a month to pay for mass transit expenses, the publication Business Insurance said.

Other plans would allow direct pay for transportation expenses and set up van pools.