Effective Tax Rates, Firm Size and the Global Minimum Tax

This paper documents new facts on corporate taxation and the revenue potential of corporate minimum taxes, leveraging firm-level tax returns from 16 countries. First, effective tax rates follow a humped-shaped pattern with firm size: small firms benefit from reduced rates, while large firms take up tax incentives, leaving mid-sized firms with the highest effective rates. On average, the effective tax rate for the largest 1 percent of firms is 2.2 percentage points lower than the average effective tax rate for the top decile of firms. Second, although statutory tax rates are above 15 percent in all sample countries, over a quarter of top firms face an effective rate below 15 percent, challenging the simple tax haven versus non-haven dichotomy. Third, a simple 15 percent domestic minimum tax for the top 1 percent firms could raise corporate taxes by 14 percent on average across countries, absent behavioral responses. In contrast, the global minimum top-up tax would only raise a quarter of this revenue due to its generous deductions and smaller number of firms in scope.