You have several options in deciding on your corporate structure. There are advantages and disadvantages to each one and you should pick what works best for your situation. Make sure to get legal and financial advice before making your final decision. Different people will expound the virtues and advantages of one form of business and the pitfalls of another. Opinions are personal, but "facts" are "facts". You need to seek out coaches who have done it one way and those who have done it the other. Get all of the case history you can, not in a deck-side conversation, but in detail. Here is a quick overview followed by more detailed descriptions.
501.c.3 The head coach can be CEO of the club and president of the 501.C.3 Not for Profit Corporation. The coach cannot personally totally control or own this type of club. It is required by law to be board governed although the board does not have to be composed of parents. Family, friends and supporters can be the board members. However, the coach is still an employee of the board. Parents are also needed in voluntary positions even if they are not on the board. In some states the swim club as a 501c3 corporation does not automatically exempt them from real estate taxes. An attorney can guide you. While not for profits have their advantages, please keep in mind no one can personally own a not-for-profit 501.c.3 corporation.
Sub-s or LLC (Limited Liability Corporation). The coach is the CEO of the corporation. A separate 501c3 not for profit that acts as a booster board can be formed although it must have a stated purpose other than just to support the coach’s for profit corporation! The for profit corporation contracts pool rental or owns the facility. The corporation can also hold a retail sellers license for swim shop related business, selling to the swimmers on the team.
Sole proprietorship or partnership. This is the simplest form of business to establish. There is no initial set-up cost; the business can be established online. However, all finances including profits and losses are tied to the coach’s personal income and taxes. All risk and liability is assumed by the coach. This is not an advisable form of business for a coach who plans to grow into a large organization with multiple employees. In fact, in a sole proprietorship or partnership, employees must be independent contractors and meet the requirements associated with independent contractor status. Check with an attorney. It is also more difficult to entice parent volunteers since profits from their effort go to the coach’s personal business rather than to the team general fund.