The Washington Court of Appeals decided that Pilates classes are taxable physical fitness services.
Physical fitness services are taxable as retail sales. However, instructional lessons such as martial arts or yoga are not taxable.
The difference between a physical fitness services and instructional lessons is that exercise is the primary focus in a physical fitness service while the activity is the primary focus of an instructional lesson.
Because of the primary focuses of a Pilates class is exercise, it is considered a taxable physical fitness service.