檢測可能的租稅漏洞－－台灣案例

Detecting Possible Taxation Loopholes The Case of Taiwan

本文提出一套程序，來檢測所得税制中可能存在的租税漏洞及其成因。利用財政部所提供的申報資料電子檔，我們發現從2000到2003年間，在税法沒有變動的背景下，綜合所得税的重分配效果竟出現了令人困惑的下降。我們探究這個現象發生的原因，最後連結到一個與捐贈扣除額有關的漏洞。我們針對「漏洞在1997年即已開啟，何以到了 2001年之後才漸為富人所用」這個謎題提出解釋，並將這個租税漏洞所造成的鉅大影響以各種模擬及量化的方式呈現。本文的標準化程序亦可適用於檢測其他國家的相似情況。

This paper proposes a series of procedures for the detection of the existence and causes of possible loopholes in the income tax system. Using Taiwan’s micro tax return data, we find a puzzling decline in the redistributive effect of the individual income tax system during the period from 2000 to 2003, without background changes in the tax law. We investigate why this occurred, eventually relating the phenomenon to a loophole involving charitable donations deductions. We offer explanations why this peculiar donation practice was not common until 2000, provide evidence of the timing behavior in 2003, and demonstrate how this tax avoidance scheme had a dramatic negative impact on individual income tax revenue. Our detection procedures are summarized and standardized, and may be extended to similar cases for other countries.