Wagstaff, A. and Van Doorslaer, E. (2001). What makes the personal income tax progressive? A comparative analysis for fifteen OECD countries International Tax and Public Finance, 8(3):299--316.

In this paper, we explore the roles of tax credits, rate structures, allowances and deductions in determining the overall progressivity of net income tax liabilities in fifteen OECD countries. Three clusters emerge: (i) the rate-structure countries, Australia, France, Italy, the Netherlands and Spain, where the rate effect is the dominant (but not the only) source of progressivity of gross and net tax liabilities; (ii) the allowance countries, the English-speaking countries other than Australia, where allowances are the dominant source of progressivity; and (iii) the mixed structure countries, Belgium, Finland, Germany and Sweden, where roughly half of the progressivity of gross tax liabilities is attributable to the rate structure.