In Duplum Rule
Also known as: In Duplum Rule, Statutory In Duplum, Section 103(5) Cap.
What is In Duplum Rule?
The in duplum rule is a common-law and statutory principle that caps the total of arrear interest, fees and charges at an amount equal to the unpaid capital at any given time. Section 103(5) of the NCA extends it statutorily to all regulated credit agreements, continuing to operate even after litigation commences.
Drafted and reviewed by
Attorney & Founder, My-Contracts.co.za · Legal Practice Council of South Africa (LPC F17333)
Definition and context
The in duplum rule is an ancient rule of South African common law, restated by the Supreme Court of Appeal in Standard Bank of South Africa v Oneanate Investments (Pty) Ltd 1998 (1) SA 811 (SCA). It provides that unpaid interest on a debt may not, while the debt remains unpaid, exceed the amount of unpaid capital. The rule operates automatically and is not dependent on the debtor raising it. Once litigation commences the common-law rule is traditionally suspended under Oneanate, but section 103(5) of the National Credit Act 34 of 2005 (NCA) has modified this position for regulated credit agreements.
Section 103(5) of the NCA provides a statutory "super" in duplum cap. It prohibits the aggregate of interest, initiation fees, service fees, credit-life premiums, default administration charges and collection costs that accrue during any period of default from exceeding the unpaid balance of the principal debt at the time of default. Unlike the common-law rule, the statutory cap continues to operate even after litigation has been commenced: Nedbank Ltd v National Credit Regulator 2011 (3) SA 581 (SCA). When the consumer makes a payment that reduces the interest and charges below the capital balance, the cap releases and further interest may accrue, always subject to the running cap.
Practically, the rule imposes a hard ceiling on lender recovery against defaulted consumers. Credit providers must track arrear interest and charges separately from capital, freeze accrual once parity is reached, and reflect the frozen balance accurately in section 129 demand letters and summonses. Non-compliance exposes the agreement to challenge under section 90 (unlawful provisions) and reckless-credit consequences under section 80. For sureties, the rule applies pari passu to their obligations because section 103(5) operates on the underlying debt.
Where this term lives in law
National Credit Act 34 of 2005
Sections: 103, 103(5)
Regulates consumer credit, credit providers, and the in duplum rule in South Africa.
Frequently asked questions
What is the difference between common-law and statutory in duplum?
The common-law rule (Oneanate) caps unpaid interest at the capital amount and is suspended on litigation. The statutory rule (section 103(5) NCA) caps the aggregate of all costs and charges at the capital at default, and continues to operate even after litigation.
Does in duplum apply to sureties?
Yes. Because suretyship is accessory to the principal debt, the cap that applies to the principal debtor also limits the surety's liability. A surety cannot be pursued for interest that the principal debtor could not have been charged.
Does in duplum apply to home loans above R1 million to juristic persons?
The common-law rule does. The NCA statutory cap does not apply to agreements falling outside the NCA (e.g. juristic persons above R1 million turnover), so only the weaker common-law Oneanate rule applies.
When does the in duplum cap "release"?
When a payment reduces the accrued interest and charges below the capital amount, further interest and charges may accrue up to the cap. The cap is dynamic and recalculated on each payment or default event.
Can a creditor contract out of in duplum?
No. Section 90(2)(c) of the NCA declares provisions that purport to waive statutory protections unlawful. Common-law in duplum is also a rule of public policy and cannot be waived.
Contract templates using this term
2 templates reference In Duplum Rule.