Limited liability companies are easy to maintain while remaining extremely flexible, so it's not surprising that it is a popular choice among businesses of all different shapes and sizes. Often, owners of an LLC are self employed or run smaller businesses, where the simplicity of pass through taxation and a lack of annual requirements makes a lot of sense. Since the profits and losses are reported directly on the owners personal tax returns, filing taxes is much easier.
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.