If your LLC is a single-member LLC you must report it on Schedule C on your personal tax return. If your LLC is a multi-member LLC you must report it as a partnership, unless you and your spouse are the only members and you live in a community property state.
Utah LLCs will be treated as partnerships for tax purposes. Partnership tax treatment is advantageous because the earnings of a partnership are treated as the earnings of its partners. No separate tax is imposed on the partnership entity.
To give your business S Corp tax status, you complete Form 2553 with the Internal Revenue Service (IRS). If you start your business as a Utah LLC, you have to complete Form 8832 to elect corporation status before you can begin filing Form 2553 to elect S Corp status.