When a padel court has no roof, normally the local authority does not count it as a building, but as a removable installation, in this case it will be sufficient to pay local taxes. However, some municipalities claim that the metallic structure and glass are considered construction, requiring the project of an architect or engineer. It is also an important aspect if you are going to carry out commercial or business activities. All this depends on the municipality and you should inform yourself at your town hall.