"Government encourages the elderly and people with disabilities to submit their applications for special votes by the 17th of April," acting Government Communications and Information System CEO Harold Maloka said in a statement.
"All registered South African voters are urged to exercise their democratic right to vote on the prescribed days."
A special vote allowed registered voters who could not vote at their voting station on election day to apply to vote on 5 and 6 May.
The elderly and people with disabilities could apply for a special vote.
The deadline to apply is 17:00 on Thursday.