We propose here a new PF account of the that -trace effect. Adopting the phase-based theory of the syntax-phonology interface and independent principles of prosodic restructuring, we propose that the complementizer that cannot form a prosodic phrase on its own. We show that this analysis straightforwardly derives the core paradigm surrounding the that -trace effect and its well-documented exceptions triggered by focus, adverbs, parentheticals, resumption, and right node raising. We further argue that the relevant prosodic condition can be derived from the interaction of the Lexical Category Condition ( Truckenbrodt 1999 ) with Prosodic Vacuity ( Kandybowicz 2015 ), within the Match Theory of syntax-prosody correspondence ( Selkirk 2011 ).