In the European Union (EU), financial market integration has been slow and only in the aftermath of the Eurozone crisis, the EU took steps toward creating a banking union. One of the main elements consists of the Single Supervisory Mechanism and attributes the European Central Bank (ECB) the task of supervising the major European banks. How are executive actors, with a specific focus on the European Central Bank, held accountable to a democratically elected authority, while keeping independent from political interference? To address this question I investigate systematically the oversight relationship between the ECB and the European Parliament (EP) in the Banking Union and, specifically: a) how and why Members of the EP (MEPs) contest ECB supervisory decisions, and b) how and why the ECB is responsive to such parliamentary questions. Using an innovative dataset on ECB hearings before the EP in the period between 2013-2024, the paper employs, first, structural topic modelling to estimate the policy topics that most prominently feature in individual questions and, later, assesses disagreement based on the semantic distance between the policy positions articulated by the two institutions. The empirical analysis considers economic (such as bank scandals), and national factors (for example, MEPs’ party affiliation, public support, trust in the ECB, and size of the parliamentary committee) that might affect MEPs’ scrutiny and ECB’s answers.