The respondents were trustees of the Kon Leech Trust. The Trust paid R4,125 million to ABSA Bank (appellant) pursuant to a second agreement concluded on 7 October 1993. This agreement was part of a complex property transaction involving the consolidation and subdivision of land and financing for a development called Needwood Village. Under clause 9.2 of the second agreement, the amount was to be paid by the Trust to ABSA in "full and final settlement" of ABSA's claim against the Trust in case number 11257/1993. The respondents subsequently instituted action claiming R2,425 million (later amended to R1,762,931) on the basis that this portion was paid in the mistaken belief that it was owing, when in fact, due to the in duplum rule, it was not owed. The in duplum rule provides that interest ceases to run when unpaid interest equals the outstanding capital. The original loan under the first agreement (7 October 1987) was R850,000. Evidence showed that there had been discussions about consolidation of various debts into one account. The trustees disputed the amount owing but agreed to pay R4,125 million to secure advantages under the second agreement.
The appeal succeeded with costs, including costs of two counsel. The order of the court a quo was set aside and replaced with an order dismissing the plaintiffs' action with costs, including the costs of two counsel.
For a claim based on condictio indebiti to succeed, the plaintiff must prove that payment was made in the actual mistaken belief that it was owing. Where payment is made despite a belief or knowledge that the amount (or a portion thereof) is not owing, but for other reasons such as securing commercial advantages or avoiding litigation, the condictio indebiti does not lie. The nature of the mistake (whether relating to interest rates, prescription, or the in duplum rule) is immaterial: if an amount is paid in the belief that it is not owing for reason A, and later appears not to be owing for reason B, it remains a payment made in the belief that it was not owing, and the condictio indebiti is not available.
The court noted that it was not necessary to deal with the other defences raised by the appellant (including novation, waiver and renunciation of the benefits of the in duplum rule, compromise, and lack of tender of restitution) given the finding on the essential element of mistaken belief. The court also observed that Mrs Leech, who was one of the trustees and the first respondent, did not give evidence, which appears to have been noted but not determinative. The court commented that it was not surprising that appellant's counsel did not pertinently challenge evidence about what the trustees would have done had they known about ultra duplum interest, as the case the appellant had to meet was that payment was made in the belief it was owing under the first agreement, which was conclusively disproved.
This case clarifies the requirements for the condictio indebiti in South African law, particularly the essential element of mistaken belief. It establishes that payment made for commercial advantage or to secure benefits under an agreement, even where the quantum of debt is disputed, does not constitute payment made in the mistaken belief that the amount was owing. The case reinforces that the condictio indebiti requires actual subjective belief that the payment was owing at the time of payment, not merely a later discovery that the payment was not legally required. The case also demonstrates the importance of the evidence of the actual decision-makers (trustees) in determining their subjective belief at the time of payment. It is significant for commercial transactions where parties may agree to pay disputed amounts as part of broader settlement or restructuring arrangements.