The Protocol on Ireland/Northern Ireland governs the trading regime for goods applicable to Northern Ireland following the UK’s decision to withdraw from the European Union. Since its entry into force, it has been the subject of much criticism, not least because some hold it responsible for the application of new barriers to trade in goods between Great Britain (GB) and Northern Ireland (NI). This paper contends, however, that any assessment of the trade-related implications of the Protocol must also take into account another international legal instrument governing the EU-UK post-Brexit trade relationship – that is, the EU-UK Trade and Cooperation Agreement. This article examines the relationship between the Protocol and theTCA, how their interaction has exacerbated post-Brexit barriers to trade between GB and NI and argues that a renegotiation of the TCA may offer the best opportunity to address many of the post-Brexit GB-NI trade frictions that have proved so controversial.