Policy debate on the implications of the Transatlantic Trade and Investment Partnership (TTIP) for Turkey has focused almost exclusively on “how” Turkey can/will take part in a forthcoming transatlantic deal. Turkey's association with a TTIP has largely been conceived as an inevitable and beneficial policy choice to re‐engage Ankara with the Atlantic alliance and emerging transatlantic trade framework. The arguments for extending TTIP to Turkey have mostly been built upon a conventional understanding of preferential trade agreements. The debate has not provided a comprehensive assessment of costs and benefits for Turkey's exclusion from or joining TTIP as it dismissed multiple dimensions of the “deep integration” agenda which underpined the transatlantic talks. This paper intends to contribute to the “why” debate with a thorough analysis of critical issues on the transatlantic agenda by evaluating economic and policy implications of TTIP both for exclusion and association scenarios together with associated compliance and adjustment costs.