I recently formed a limited liability company (LLC). The LLC has no employees. Do I need a separate Federal Tax ID number for the LLC?

No, you will not need a separate Federal Tax ID number for the LLC if you are the sole owner of the LLC and the LLC has no employees. If you are the sole owner of the LLC and the LLC has employees, you will need to get a separate Federal Tax ID number, if you choose to have the LLC report and pay employment taxes with respect to employees of the LLC. If you are not the sole owner of the LLC, you will need a separate Federal Tax ID number for the LLC. See Notice 99-6, 1999-1 CB 321.

For IRS purposes, how do I classify a limited liability company? Is it a sole proprietorship, partnership or a corporation?

A limited liability company (LLC) is an entity formed under state law by filing articles of organization as an LLC. Unlike a partnership, none of the members of an LLC are personally liable for its debts. An LLC may be classified for Federal income tax purposes as if it were a sole proprietorship (referred to as an entity to be disregarded as separate from its owner), a partnership or a corporation. If the LLC has only one owner, it will automatically be treated as if it were a sole proprietorship (referred to as an entity to be disregarded as separate from its owner), unless an election is made to be treated as a corporation. If the LLC has two or more owners, it will automatically be considered to be a partnership unless an election is made to be treated as a corporation. If the LLC does not elect its classification, a default classification of partnership (multi-member LLC) or disregarded entity (taxed as if it were a sole proprietorship) will apply. The election referred to is made using the Form 8832 (PDF), Entity Classification Election. If a taxpayer does not file Form 8832 (PDF) , a default classification will apply.