This paper examines how tightening the countercyclical capital buffer (CCyB) in Germany affects bank lending to firms, using highly granular loan‑level data from the European Central Bank. Exploiting the 2022 German CCyB increase and employing a difference‑in‑differences identification strategy with Austria as the control group, the authors show that German banks reduce corporate lending volumes and raise lending rates – changes that materialize immediately after the policy announcement, well before implementation. Crucially, the tightening disproportionately affects small and medium‑sized enterprises (SMEs), which face both reduced credit supply and higher borrowing costs, while bigger firms remain largely unaffected. The results highlight the importance of announcement effects in macroprudential policy and point to significant distributional consequences across firm sizes.