Markus Diller

Komplexität steuerrechtlicher Normen — Ein spieltheoretischer Erklärungsansatz

ZusammenfassungDer Beitrag analysiert Ursachen für steuerliche Komplexität. Um diese zu identifizieren, gehen wir zunächst von Einkommen maximierenden Steuerpflichtigen und einem Einnahmen maximierenden Staat aus, die als Gegenspieler fungieren. Mit einem spieltheoretischen Ansatz identifizieren wir, unter welchen Bedingungen steuerrechtliche Komplexität entsteht und welche gegenläufigen Effekte zur Komplexitätssenkung in Rechnung gestellt werden müssen. Ferner modifizieren wir unsere Annahmen um ein bereits existierendes Niveau an Komplexität, durch Einführung eines allein ein Haushaltsbudget deckenden Staates sowie durch eine Differenzierung zwischen Steuersatzund Bemessungsgrundlageneffekten.AbstractWe analyze the economic determinants of tax complexity. In order to identify the main drivers of tax complexity, we assume that after-tax returns-maximizing taxpayers and revenue-maximizing tax authorities behave as counterparts. We then apply game theory to identify under which conditions tax complexity is reduced and which trade-offs have to be taken into account. Furthermore, we modify our assumptions by introducing tax authorities that only have to satisfy an exogenous budget, by taking into account that complexity already exists and by separating the effects for tax rates and tax bases.

The Epidemiology of Tax Avoidance and Tax Evasion

We propose a model that captures tax avoidance as an investment under uncertainty: searching for tax loopholes or developing legal avoidance schemes is associated with costs; the tax benefit is however uncertain. Its height depends on whether or not the tax agency agrees with the chosen avoidance model. We find that increasing the tax rate causes taxpayers to devote more (less) effort to tax optimization if the variance of tax savings is below (above) a certain threshold. Using an epidemiological SIS-model we account for social contagion effects. We find that there exist parameter constellations in which increasing the tax rate causes both individual avoidance effort and the number of tax avoiders to increase, implying that tax revenue decreases. If tax avoidance is a precondition for tax evasion, the number of tax evaders can increase if more individuals avoid taxes as a consequence of an increase in the tax rate. Thus, increasing the tax rate can cause overall compliance to shrink even if all taxpayers evade by less. This happens if expected tax benefits are rather predictable.

Tax-Optimal Step-Up and Imperfect Loss Offset

In the field of mergers and acquisitions, German and international tax law allow for several opportunities to step up a firm’s assets, i.e., to revaluate the assets at fair market values. When a step-up is performed the taxpayer recognizes a taxable gain, but also obtains tax benefits in the form of higher future depreciation allowances associated with stepping up the tax base of the assets. This tax-planning problem is well known in taxation literature and can also be applied to firm valuation in the presence of taxation. However, the known models usually assume a perfect loss offset. If this assumption is abandoned, the depreciation allowances may lose value as they become tax effective at a later point in time, or even never if there are not enough cash flows to be offset against. This aspect is especially relevant if future cash flows are assumed to be uncertain. This paper shows that a step-up may be disadvantageous or a firm overvalued if these aspects are not integrated into the basic calculus. Compared to the standard approach, assets should be stepped up only in a few cases and — under specific conditions — ata later point in time. Firm values may be considerably lower under imperfect loss offset.