If it's for a new profession or trade you can't deduct it. I'm a CPA, if I go to law school I can't deduct it. If I take auto repair classes at a technical school and open a garage, I can't deduct the costs of the training prior to opening the business. Once yo become a Yoga Instructor, you can deduct any additional classes you take. So, after your a yoga instructor you take a class in a different type of massage, you can deduct it because "it maintains or improves skills needed in your present work." I hope this helps.
