Hauer first became a member of the Bundestag in the
2013 German federal election, representing the
Essen III district. In parliament, he was a member of the Committee on the Digital Agenda (2018–2025) and the Finance Committee (2013–2025). In this capacity, he was the parliament's
rapporteur on the
Wirecard scandal. In addition to his committee assignments, Hauer is part of the German Parliamentary Friendship Group for Relations with the States of Central America. Since 2015, Hauer has been leading the CDU in Essen. In the negotiations to form a
Grand Coalition between the Christian Democrats (CDU together with the Bavarian
CSU) under the leadership of
Friedrich Merz and the
SPD following the
2025 German elections, Hauer was part of the CDU/CSU delegation in the working group on public finances, led by
Mathias Middelberg,
Florian Oßner and
Dennis Rohde. == Other activities ==