The Austrian adoption fee has recently attracted renewed attention due to a decision of the Federal Fiscal Court (BFG) and, incidentally, has raised several fundamental issues of international tax law. At its core lies the question of whether the adoption fee qualifies as a “tax on wealth” and whether tax treaties, particularly under the OECD Model Tax Convention, may be applicable. This provides an opportunity to examine the substantive and personal scope of tax treaties, their application to “ordinary” and “extraordinary” taxes, and the implications of the absence of effective double taxation on the basis of the OECD Model Tax Convention.