Permit Process and Requirements to make office in a Room

[Charles Cooper]

Hello fellow BP members, anyone in the California area have any experience with converting an office or loft into a actual room on title. For example.

My property has 3 bedrooms but I also have a separate room that I use as an office. The room has an actual door with entrance and an exterior window. If I add a closet, would that be considered a room? What are the fees with permits and what not? Thanks!