It depends on the nature and size of the proposals. Not all types of development require planning permition, hence the section of Permitted Development in the planning system. If you don’t require planning permission for the development, the LPA would also not need notify any interested parties in order to get any objections within the 21 days.

Even though sometimes you don’t need to let them know and get their permission about your future development, as always it is best practice to speak to a neighbour and try to get them on-board with your proposals to avoid any future conflict.