Who decides on the final form of the ballot text?

ORDINANCE ON POLITICAL RIGHTS

(Adopted 1978; last amended 2012)

http://www.admin.ch/opc/de/classified-compilation/19780105/index.html

2. Abschnitt: Abstimmungen

Art. 3 Vorbereitung

(1) Die Bundeskanzlei trifft die nach den gesetzlichen Vorschriften zur Durchführung der Abstimmung nötigen Massnahmen.

(2) Sie arbeitet zusammen mit dem zuständigen Departement die Erläuterungen aus und unterbreitet sie dem Bundesrat zur Beschlussfassung.
 

FEDERAL ACT ON POLITICAL RIGHTS

(Adopted 1976; last amended 2009)

http://www.admin.ch/ch/e/rs/161_1/index.html

Title 2. Votes

Art. 11 Proposals submitted to a vote of the People, ballot papers and explanatory statements

(1) The Confederation shall provide the cantons with the proposals to be submitted to a vote of the People and the ballot papers.

(2) Each proposal shall be accompanied by a short, objective explanation fromthe Federal Council, which shall also take account of the opinions of significant minorities. The proposal must contain the wording of the questions on the ballot paper. In the case of popular initiatives and referendums, the initiative committee shall inform the Federal Council of their arguments and the Federal Council shall take such arguments into account in its explanatory statement…

In the case of a referendum on a federal act or a constitutional change, the question merely states: “Do you support the referendum on (name of act/law) - yes or no?