Requirements for a referendum to pass
Bulgaria
Answer
Optional referendum - simple majority
Source
The proposal subjectto the referendum shall be considered accepted if ?yes? votes are more thanhalf of all votes.
Act on Direct Participation of Citizens in Government and Local Government of29 May 2009, Article 23.3
http://www.lex.bg/bg/laws/ldoc/2135636485 (inBulgarian)
