noun
add-on method; add-on interest
A method of calculating interest on a loan where the total interest is determined upfront based on the original principal, then divided into equal installments. Common in consumer finance.
アドオン方式で計算すると、実質金利は表示よりも高くなることがある。
When calculated using the add-on method, the effective interest rate can be higher than the stated rate.
実質金利 is the effective interest rate, which is often higher than the nominal rate under the アドオン方式.
Compound of アドオン (add-on) and 方式 (method, system). The term is a direct borrowing from English 'add-on' in financial contexts.