Johannesburg - Almost four million people had submitted their tax returns by Monday morning, the SA Revenue Service (Sars) said.
"At 09:00, over 3.8 million South Africans had already filed their 2013 income tax return with Sars," said spokesperson Adrian Lackay.
He said more than two million taxpayers had used the Sars e-filing service, and 1.8m had filed electronically at a Sars branch.
Almost two million tax refunds had been paid out by Sars, to the value of over R12.8bn.
"At the same point last year, just over two million refunds had been paid out, worth just over R11.4bn in total."
The deadline for the submission of tax returns by non-provisional taxpayers (individuals who earn an income from an employer) is November 22.
Lackay said the annual tax season served as a key determinant of people's levels of compliance with the country's laws. He warned that criminals used the tax season to take advantage of unsuspecting taxpayers.
"Taxpayers must beware of e-mails that ask for personal, tax, banking and e-filing details.... Sars will never ask taxpayers for such information in an e-mail."
Lackay said Sars would also not request banking details over the phone, or via e-mail, sms, or websites.