It's not a new law, but a new crackdown by the Missouri Department of Revenue. Officials say the studios fall under the category of "recreation centers" and the state sales tax statute rules they must charge sales tax.

Some studio owners like Jennifer Drewing say they don't think their businesses should have to charge sales tax. Drewing found her love for Pilates after she had a back injury and turned to the exercise as an alternative to surgery.

"Once I became certified and rehabbed my own back, I developed a passion for it and decided to spread that passion to other people," Drewing said.

Now she'll have to charge both state and local sales tax of her customers. Last month, the Missouri Department of Revenue sent out a letter to yoga and Pilates studios saying they had to pay the tax. Drewing says it's been tough charging her customers extra.

"I feel bad about it because this is a service industry and to my knowledge, services were not to be taxed," Drewing said.

The Department of Revenue insists it's not a new law, but they're simply enforcing the law fairly now.

"This is an existing sales tax that applies to businesses that provide these types of services," Missouri Department of Revenue Communications Director Ted Farnen said.

But Drewing says a Pilates studio is different from a gym.

"It's more than working out," Drewing said. "It's more of an overall experience that people are getting when they come in here."

Some studio owners say they should not be taxed because they provide a spiritual service. The Department of Revenue will consider appeals on a case-by-case basis.