An LLC that does not want to accept its default federal tax classification, or that wishes to change its classification, uses Form 8832, Entity Classification Election (PDF), to elect how it will be classified for federal tax purposes. Generally, an election specifying an LLC’s classification cannot take effect more than 75 days prior to the date the election is filed, nor can it take effect later than 12 months after the date the election is filed. An LLC may be eligible for late election relief in certain circumstances. See About Form 8832, Entity Classification Election for more information.
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.