Is it legal for developers to change the use of underground garages without authorization?

Illegal, in the "Code for Planning and Design of Urban Residential Areas", the relevant aspects of urban residential areas are specified in detail. A certain proportion of the garage is one of the standards. For example, the specification stipulates that the parking rate of residents' cars is not less than 10%.

According to China's property law

Article 142

Ownership of buildings and other facilities built by construction land owners.

The ownership of buildings, structures and ancillary facilities built by the right holder of construction land belongs to the right holder of construction land, unless there is evidence to the contrary.

Extended data:

According to the law, the proportion of the garage belongs to the owner. The ultimate goal of buying commercial housing is to live. In addition to the construction area indicated in the property certificate, there are a series of auxiliary and supporting facilities for the normal living function of the house. Without these ancillary and supporting facilities, the living function of the house would be incomplete.

In an urban residential area, the parking spaces necessary for residents' normal life should not be less than 10%, and 10% parking spaces are an indispensable part of the normal operation of housing. This 10% parking space is used for parking from the source; Judging from the benefit range of use efficiency, it is the owner of the community. Therefore, property rights belong to all owners of the community.

References:

Baidu Encyclopedia-People's Republic of China (PRC) Property Law