The objective of this paper is to revisit as well as empirically examine an old but still discussed postulate, the Khaldun-Laffer curve, on the basis of personal income tax by making use annual time-series data for Turkey for the period 1970-2015. The findings of the paper confirm the validity of the Khaldun-Laffer curve hypothesis. In addition, we infer that the optimal tax rate that maximizes the tax revenue generated from personal income taxation in Turkey is 15.03 percent. This rate is well-below than the current rate which we estimate as 15.37 percent, implying that Turkey’s current tax rate for personal income tax takes place in the prohibitive range of the Khaldun-Laffer curve. These findings suggest that the current tax rate should be lowered and to its optimal level to collect more tax revenue. Getting down the current rate to its revenue-maximizing rate not only would it enable the Turkish authorities to collect more revenues with a relatively lower rate, but also would allow them to minimize the substitution effects of personal income tax while maximizing the income revenues from it.

中文翻译：

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回顾Khaldûn-Laffer曲线：基于个人所得税的土耳其分析

本文的目的是通过使用土耳其1970-2015年期间的年度时间序列数据，在个人所得税的基础上，重新审查和经验检验旧的但仍在讨论的假说Khaldun-Laffer曲线。本文的发现证实了Khaldun-Laffer曲线假说的有效性。此外，我们推断，使土耳其个人所得税产生的税收最大化的最佳税率为15.03％。该税率远低于我们估计的当前税率15.37％，这意味着土耳其当前的个人所得税税率发生在Khaldun-Laffer曲线的禁止范围内。这些发现表明，应降低当前税率并将其降至最佳水平，以收取更多的税收。