In a few states, you must take an additional step to make your company official: You must publish a simple notice in a local newspaper, stating that you intend to form an LLC. You are required to publish the notice several times over a period of weeks and then submit an "affidavit of publication" to the LLC filing office. Your local newspaper should be able to help you with this filing.
A limited-liability company ("LLC") is commonly referred to as a "hybrid" business structure, meaning that it shares characteristics of both a corporation and a sole proprietorship. It allows its owners to insulate themselves from personal liability for business debts, does not require the payment of separate business taxes (the tax "passes through" to its owners), allows for a great deal of flexibility with regards to its organizational structure, and is subject to fewer regulations and restrictions than are other types of business structures. Establishing such a company in Wisconsin is a rather straightforward process.
On the other hand, if you are not responsible for its tax, then you should declare the equipment in Part III of the Business Property Statement (Equipment belonging to others). Where equipment is declared in Part III of the Business Property Statement, the Assessor will also send a Notice to File to the person reported as the equipment's actual owner.