Calculator
Arrears interest calculator
Estimate simple interest on overdue rent or levies.
The formula
Interest = arrears amount × (annual interest rate ÷ 100) × (days overdue ÷ 365). Total owing = arrears amount + interest. Daily interest = arrears amount × (rate ÷ 100) ÷ 365. This is simple, non-compounding interest.
Worked example
R10 000 in arrears at 11.75% for 60 days accrues about R193 in simple interest, for a total of about R10 193.
Assumptions & limitations
Uses simple (non-compounding) interest on a 365-day year. The interest rate must be one lawfully agreed or permitted (e.g. within the National Credit Act / the rate set by trustees for a scheme).
The in duplum rule generally caps accrued interest at the outstanding capital, and lawful rates are limited — confirm the applicable rate and limits. Not legal advice.
Informational only — not financial or legal advice. Confirm the rate and limits against your lease, the scheme’s rules and the applicable legislation.
Arrears interest calculator — FAQ
How is interest on arrears calculated?+
This calculator uses simple (non-compounding) interest: arrears amount × annual interest rate × (days overdue ÷ 365). For example, R10 000 in arrears at 11.75% for 60 days accrues about R193. The total owing is the original arrears plus that interest.
What interest rate can I charge on overdue rent or levies?+
You may only charge a rate that is lawfully agreed or permitted — for instance a rate within the National Credit Act, or the rate set by trustees for a community scheme. There is no automatic statutory rate; confirm the applicable rate and its limits before applying it.
What is the in duplum rule?+
The in duplum rule generally caps accrued interest at the amount of the outstanding capital. Once unpaid interest equals the capital still owing, interest stops running until the balance is reduced. This calculator does not apply that cap automatically, so check whether it limits your figure.