International and European tax law is important for national law, in particular for corporate income tax, dividend tax and income tax. De Wilde's research theme is the effect of EU law and international and European (tax) law on the income and profit tax systems of countries. This is part of the research program Fiscal autonomy and its limits.

In addition, the board of Erasmus School of Law has asked De Wilde - as a nationally and internationally recognized scientist with connecting ability - for further substantiation of the academic leadership of the Tax Law section.