This article explores in more detail some of the timing issues that may arise when a new tax treaty becomes applicable or when there is a relevant change in the factual situation of the taxpayer, both resulting in a shift in the allocation rights of the tax treaty states involved. In both cases, the question is to what extent this change in allocation rights is applicable ratione temporis. It is concluded that this question cannot be answered in a general sense. In each situation, it boils down to a case-by-case analysis that must be performed under both international and national law.
Intertax