ISP Working Paper Number 07-21

Global Reform of Personal Income Taxation, 1981-2005: Evidence from 189 Countries

Klara Sabirianova Peter, Steve Buttrick, and Denvil Duncan, December 2007

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Abstract:

In this paper we use a panel of 189 countries to describe the salient trends that have emerged in national personal income tax systems spanning the twenty five year period from 1981 to 2005. Using complete national income tax schedules with statutory rates, thresholds, country-specific tax formulas and other information, we calculate actual average and marginal tax rates at different income levels as well as time-varying measures of structural progressivity and complexity of national tax systems. Overall, our analysis shows a significant transition from complex, graduated tax schedules that featured multiple tax brackets and stair stepped tax rates to simpler, flatter tax schedules distinguished by fewer tax brackets and lower rates. The emerging trend toward flat tax schedules is also highlighted. We show that frequent alterations of tax structures have diminished the overall progressivity and complexity of national tax systems; however, the degree of this change varies considerably by country group.