中文摘要 租稅公平原則是稅法的核心原則,而量能課稅更是實踐租稅公平之關鍵。在稅制的演進過程中,所得稅相較於其他稅制而言,是較能符合量能課稅原則。故作為所得稅制下課稅客體的課稅所得便與量能課稅原則有著密不可分之關係。 由於我國所得稅法對於所得稅之課稅客體並無較為明確的定義性規定,因此也造成諸多稅捐實務上對於所得認定之爭議,而在司法院大法官釋字第三一五、五○八與六○七號解釋更是明顯之例。 為了探尋我國所得稅制下的所得概念,因此本研究首先彙整與闡述各種的所得概念之理論。再者,由於我國營利事業所得稅對於營利事業諸多財務事項之認定,除所得稅法另有規定之外,也多牽涉到財務會計學以及財務會計準則公報的認定標準;本研究基於此,亦予以探究在財務會計學與財務會計準則公報下的所得概念。此外,承接先前對於各種所得概念之彙整與闡述,本研究亦進一步分析各種所得概念下之量能課稅間之關係。最後,本研究再予以探尋我國所得稅制是建構於何種所得概念之理論上。而在本研究之末了,亦針對司法院大法官釋字第三一五號解釋予以深入剖析與探討之。
Abstract Equity in taxation is the core principle of tax laws, while “taxation according to ability” is the key to fair taxation. In the history of tax systems, income tax is more consistent with the principle of “taxation according to ability” than are other taxes. Therefore, “taxable income”, object of tax, and the principle of “taxation according to ability” are significantly related. Since the Income Tax Law in Taiwan does not provide a definition of taxable income, disputes arise from taxation practices. The Judicial Yuan Interpretation No. 315, 508, and 607, are evidence of such ambiguity. To better understand the underlying income concept of the Income Tax Law in Taiwan, the study first integrates and interprets different income theories. Next, the interpretation of financial items of profit-seeking enterprises’ income tax involves: Income Tax Law, financial accounting, and the statements of financial accounting standards. The study also explores the income concept described in financial accounting and the statements of financial accounting standards. Following the integration and interpretation of different income concepts, the study analyzes the relations between the principle of taxation according to ability and various income concepts. In closing, the study investigates which income concept serves as the foundation of Taiwan’s income tax system. At the end of the study, the Judicial Yuan Interpretation No. 315 is analyzed and elaborated.