Pay Personal Property Taxes Online enables online payments for personal property tax bills received from Middlesex County. This valuable resource serves as a treasure trove of information, providing a comprehensive insight into real estate documentation within Middlesex County.Borough of Middlesex. All owners of taxable personal property are required, annually, to file a Personal Property Declaration Form M-15. Fill in the blank form formatted to comply with all recording and content requirements. A single personal property assessment is made for all taxable personal property of the owner located in the city or town. 2. What is considered individual personal property? Is the Homestead form difficult to understand and fill out? No. It simply asks for basic information. Middlesex County Warranty Deed Form.