This study considers a contrast in Mainland Scandinavian with respect to co-occurrence of a suffixal and a free-standing determiner ("double determination'') in parallel to a series of contrasts in how the suffixal determiner is realized phonologically. On the basis of the phonological evidence I propose that in Norwegian and Swedish the suffixal determiner does not belong to the same phonological domain with the root with respect to several phonological processes, in contrast to Danish. Consequently, I argue that only in the former two languages the suffixal determiner should be considered a spellout trigger and thus a phase-head. Independently of this, I propose that in all Mainland Scandinavian the head hosting the suffixal determiner has a feature [Affix], proposed by Roberts (2005), that triggers a head-movement, whereas the head hosting the free-standing determiner does not have this feature. This state of affairs offers itself as an ideal testing ground for the hypothesis that there are general grammar constraints on the distribution of movement driving features, in particular of an EPP-like feature [Affix]. I propose that [Affix] specification should be consistent within a phase, which represents an amendment to the EPP downward inheritance generalization of Biberauer et al. (2008). The absence of "double determination'' in Danish is then argued to follow from the non-phase head status of the head hosting the suffixal determiner in Danish, as this bleeds the environment for an [Affix] specification "switch''.