Postbank is to reward bigger savers with higher interest rates from Monday.
Billy Tlhabenelo, the general manager, said Postbank, which holds R1 billion of investors' money, would apply eight different interest rates to savings accounts from July 1.
Instead of being fixed at 6 percent, interest rates would now range from 2,5 percent on the smallest balances to 10,5 percent on savings of more than R50 000. The rate on the card-operated savings account would stay at 6 percent.
Tlhabenelo said people who saved more should be rewarded with higher interest.
At the same time, he said, the interest rate on Savings Certificates would rise one percent to 13,5 percent.
Postbank holds about R600 million in savings accounts and R400 million in Savings Certificates.
Money in Savings Certificates is fixed for six months and can then be withdrawn on demand.
Tlhabenelo said interest rates on Savings Certificates could not be compared to those on six-month deposits in banks.
Most Savings Certificates accounts were older than six months, so the money was effectively on call, he said.
In the past, interest on Savings Certificates had been tax-free, and the accounts had been attractive, especially to retired people, many of whom had invested the maximum of R70 000.
But interest was now fully taxed.
"Money is flowing out at a rate of about R8 million a month," he said.
Postbank would continue to cater for the small investor by offering interest on balances as low as R10, unlike most other banks, Tlhabenelo said. Interest would be calculated on daily balance, allowing depositors to earn variable interest rates as their balances fluctuated.