Is there a legally mandated filing fee and/or deposit?

Not Specified in Election Law and Constitutional Court ApplicationAdministration Procedure

Source: http://aceproject.org/electoral-advice/archive/questions/replies/286046320/230159556/Unofficial-Translation-of-Law-8-2012-on.pdf

And

http://www.mahkamahkonstitusi.go.id/index.php?page=web.PendaftaranPemohonan