As others have commented on this question, the best advice is to seek the advise of a professional, most likely a business attorney. There is more to be considered than just taxes.
You need to choose the form of business that makes sense for the type of business you are conducting, in the state you are doing business in, what your goals are, and what you feel comfortable.
Lack of action will, for tax purposes at least and perhaps for other situations as well, automatically treat you as a partnership. If not formally, then at least informally. There are benefits and risks in conducting business as a partnership. More risks than needed if not formed, have a partnership agreement, and conform to the laws of the state you're doing business in.
Again, seek professional advice. Good Luck.
**Disclaimer: Effort has been made to offer correct information; but due to the discussion forum limitations, the poster disclaims any legal responsibility for the accuracy of the poster's response**
