All formal business entities, including LLCs, are required to have a Registered Agent on file with the state at all times. The agent may be an individual or company with a physical address located in the state of incorporation. Agents must be available at all times during standard business hours (9 a.m. - 5 p.m. Monday – Friday). The role of a Registered Agent is to receive any and all of communications from the government to the business. The agent’s name and address must be disclosed as part of the company’s public record.
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.