The central bank is nowadays primarily an agency for monetary policy. It usually also has important financial stability functions, and those become more prominent during times of financial turmoil. The structure of those roles, the responsibilities given, and the range of other functions allocated vary between countries. The main issues are as follows:
What degree of independent authority does the central bank have to design policy, make policy decisions, and implement those decisions? This question also relates to the degree of influence over exchange rate policy and the setting of objectives for both monetary and exchange rate policies.
What degree of responsibility does the central bank have for financial stability? Does it have the instruments commensurate with that responsibility? What tasks are given to the central bank with respect to the regulation of financial activity and supervision of financial institutions? How well do those roles fit with others? How are objectives set?
How does the central bank go about ensuring the efficiency and robustness of the various infrastructure systems that support payment and settlement? How does ownership and operation of such systems sit with the oversight, supervision and regulation of private providers?
What other functions fit well with the core monetary policy and financial stability tasks? What are the relevant criteria? Do they differ between mature and emerging financial market environments?