Special voters will make up more than 770 000 of the votes, the Electoral Commission of SA (IEC) announced on Tuesday.
Special voters are expected to vote on May 6 and 7.
According to the IEC, a special vote allows a registered voter who can't vote at their voting station on election day to apply to vote on a predetermined day before that day.
This election, the number of special voters sits at 774 094 - double the number in 2014.
In a statement, the IEC added: "Of those whose applications for a special vote in 2019 were approved, 452 418 (58.4%) will cast their votes during a home visit by election officials, accompanied by party agents and observers. Voters granted permission for home visits are only those who cannot visit a voting station due to physical infirmity, disability and pregnancy."
The remaining 321 676 voters - 41.6% - are expected to cast their special votes at their voting stations between 09:00 and 17:00, the IEC said.
The province which has the highest number of home visits is the Eastern Cape - 85 252 - and the province with the highest number of voting station visits is Gauteng - 71 921.
The IEC has assured the public that special votes will be under stringent security watch.
"The special votes are transported and stored securely overnight at municipal warehouses and other secure locations, including local police stations on May 6 and 7, before being transported back to the voting station on election day for inclusion in the count.
"The overnight security facilities are vetted by the State Security Agency to ensure adequate security arrangements."
On Tuesday, IEC chair Glen Mashinini said transparency was the single most key factor in the commission's election process. He was speaking during the launch of the results operation centre (ROC) in Pretoria.
More than 22 000 voting stations will be opened across the country on May 8.