The in duplum rule has been part of South African law
for more than 100 years, being applied through South African case
law from as early as 1830. Literally translated, in duplum
means 'double the amount'. This common law rule provides
that interest on a debt will cease to run where the total amount of
arrear interest has accrued to an amount equal to the outstanding
principal debt. It was developed in response to considerations of
public interest, and seeks to protect borrowers from exploitation
by lenders who permit interest to accumulate unchecked. It also has
the effect of encouraging lenders to exercise their rights to be
repaid, promptly and without delay.
The National Credit Act (NCA), No 34 of 2005, incorporates a
statutory version of the in duplum rule in section 103(5),
which is commonly referred to as the statutory in duplum
rule. This section provides that "Despite any provision of
the common law or a credit agreement to the contrary, the
