The business tax structure a therapist chooses will depend on many factors. One important consideration is how tax structure affects liability.
Even companies who operate with a high level of business ethics may face litigation. A client may slip and fall in your office or an underlying condition may be aggravated by massage therapy. It is extremely important to have sufficient liability insurance and the appropriate business tax structure to protect your personal assets in the case of a lawsuit.
Business liability insurance may be obtained through an insurance broker and malpractice insurance can be obtained through a professional massage association and should be carried by every massage practitioner.
Here is a link to the IRS that discusses business tax structure. IRS Business Tax Structures.