This paper intends to investigate whether the turning points exist between tax revenue, gross domestic product, government expenditure, and gross domestic saving towards Malaysia's total external debt. The researcher implements the adaptive neuro-fuzzy inference system model to forecast the total external debt in Malaysia. The total external debt prediction then projects the three-dimensional surface diagrams to depict whether the turning points exist among the variables. This study's empirical finding reveals that the turning points are noticeable between the tax revenue, gross domestic product, and gross domestic saving toward external debt in Malaysia. However, government expenditure depicts a direct relationship with external debt. This finding demonstrates that the anomaly between the theories and scholarly activities. This study also recommends that the tax revenue be collected at maximum holding the government expenditure and gross domestic product are maximum statistics to reduce Malaysia's external debt.
Adaptive neuro-fuzzy inference system External debt Government expenditure Gross domestic product Gross domestic saving Tax revenue