Unfortunately, I found only one source for the drone regulations in Bulgaria. According to the BULATSA Air Force, each pilot must obtain permission from the Directorate General “Civil Aviation Administration” (DG CAA) before a flight. The application had to be submitted 8 days in advance. After confirmation, an airspace is reserved for the specially signed maneuver by BULATSA. I have to say, that the information relates to a publication from the year 2014, so I am not sure if there are now new laws. A request to the aviation authority has so far remained unanswered.
Helpful links: BULATSA
We have researched the listed drone regulations for Bulgaria to the best of our knowledge. We can not guarantee the correctness of the information. If you want to be on the safe side, please contact the competent aviation authority. Alternatively, you can also ask the embassy in your country for further information about the regulations. Please leave us a comment when you receive news and/or gain experience with your copter in Bulgaria!