Who decides on the final form of the ballot text?

Austria
Answer
- Mandatory referendum - Independent electoral commission
- Optional referendum - Independent electoral commission
Source
Volksabstimmungsgesetz1972 ? 9 (1)
http://www.ris.bka.gv.at/GeltendeFassung.wxe?Abfrage=Bundesnormen&Gesetzesnummer=10000530