Final answer:
An offsite improvement in a subdivision is an infrastructure or amenity upgrade outside the property boundaries that supports the services and access needed for the development, such as road or sewer upgrades. These improvements are mandated by local authorities and distinguishable from onsite improvements which are within the property itself.
Step-by-step explanation:
An offsite improvement in a subdivision refers to infrastructure or amenity upgrades that are made outside the boundaries of the property being developed but are necessary for the services and access of the said development. Examples of offsite improvements may include upgrades to public roads to accommodate increased traffic, installation of sewer lines that connect the subdivision to the municipal system, and development of regional water detention facilities that serve more than just the immediate development area.
These improvements are typically mandated by the local government to ensure that the new development does not negatively impact the surrounding area and complies with the relevant building codes and zoning regulations. They are different from onsite improvements, which are the upgrades made within the boundaries of the property, such as restrictions on accessory buildings, compliance with building setbacks from the streets and other boundaries, adherence to regulations about the size and height of buildings, and the number of rooms in each structure.