They will cast the votes.

Votes will be cast by them

Votes will be casted by them

Votes were cast by them

Votes can be cast by them

All of the above

Active Voice: They will cast the votes.

Passive Voice: Votes will be cast by them.

Future Indefinite Tense-Passive Voice

Convert the object of the Active Voice Sentence into the subject of the Passive Voice sentence.

Then use helping verb will be/shall be according to the subject of the Passive Voice Sentence.

Then use the 3rd form of Verb.

After that, use the word “by”, in order to show the doer.