The financial crisis has generated a high degree of legislative activity both in the area of substantive and procedural financial regulation and in the area of taxation of the financial sector. This article explores criteria for legislative choice (in particular for the European Union) when a given target can be addressed both by regulatory means and by fiscal burdens. Major examples include the (1) choice between capital requirements for financial institutions and the introduction of bank levies, (2) substantive constraints for executive compensation versus a "bonus tax", and (3) the relationship between the existing European regulatory regime of financial markets and the current project of a "financial transaction tax". While bank levies can play a meaningful role alongside capital requirements, both the "bonus tax" and the "financial transaction tax" seem less attractive than alternative regulatory options.