Alamo Rent A Car is offering 15% off the base rate for weekly rentals that are reserved up until Feb. 7, 2017. This promotion is to celebrate National Plan for Vacation Day on Jan. 31.

The discounted rates are applicable for travel anytime between March 1 and Aug. 31, 2017, according to Alamo.

National Plan for Vacation Day is aligned with a study called Project: Time Off, which found that 658 million vacation days go unused each year. According to the 2016 research, 49% of households plan their use of vacation time each year. Of those who plan, 51% took all their vacation time compared to just 39% of non-planners, says the study.

Project: Time Off’s “The State of American Vacation 2016” also found that those who took more vacation time had a correlation of higher happiness at home and with their jobs.

“Unused time off is not only a missed opportunity for an individual’s health, well-being, and success, but also for businesses who want the best version of their employees,” said Gary Oster, managing director of Project: Time Off. “National Plan for Vacation Day ensures our hard-earned time off is put to good use for the benefit of all.”