This paper analyzes the impact of introducing a central bank-issued digital currency (CBDC) on the operational framework of monetary policy and the macroeconomy. Using a New Keynesian model with heterogeneous banks, a frictional interbank market, and central bank standing facilities, the authors examine how CBDC adoption affects bank deposits, lending, and the central bank's operational framework. The model is calibrated to the euro area and shows that CBDC adoption leads to a reduction in bank deposits, which is absorbed by a decrease in central bank reserves. For moderate CBDC adoption levels, this results in a transition from a "floor" system to a "corridor" system, where interbank rates are determined by the interest rate corridor formed by the deposit and lending facility rates. For higher CBDC adoption levels, the loss of bank deposits is compensated by increased reliance on central bank credit, leading to a "ceiling" system. The paper finds that CBDC adoption has significant macroeconomic implications, including changes in household savings, investment, and output. The results suggest that the impact of CBDC on the macroeconomy is non-neutral, as it affects prices and macroeconomic aggregates through two channels: the remuneration of household savings and the operational framework of monetary policy. The paper also highlights the importance of the central bank's response to CBDC adoption in maintaining the stability of the monetary policy framework. Overall, the study provides insights into the potential effects of CBDC on monetary policy and the macroeconomy.This paper analyzes the impact of introducing a central bank-issued digital currency (CBDC) on the operational framework of monetary policy and the macroeconomy. Using a New Keynesian model with heterogeneous banks, a frictional interbank market, and central bank standing facilities, the authors examine how CBDC adoption affects bank deposits, lending, and the central bank's operational framework. The model is calibrated to the euro area and shows that CBDC adoption leads to a reduction in bank deposits, which is absorbed by a decrease in central bank reserves. For moderate CBDC adoption levels, this results in a transition from a "floor" system to a "corridor" system, where interbank rates are determined by the interest rate corridor formed by the deposit and lending facility rates. For higher CBDC adoption levels, the loss of bank deposits is compensated by increased reliance on central bank credit, leading to a "ceiling" system. The paper finds that CBDC adoption has significant macroeconomic implications, including changes in household savings, investment, and output. The results suggest that the impact of CBDC on the macroeconomy is non-neutral, as it affects prices and macroeconomic aggregates through two channels: the remuneration of household savings and the operational framework of monetary policy. The paper also highlights the importance of the central bank's response to CBDC adoption in maintaining the stability of the monetary policy framework. Overall, the study provides insights into the potential effects of CBDC on monetary policy and the macroeconomy.