A cabinet department or prime minister's department is a department or other government agency that directly supports the work of the government's central executive office, usually the cabinet and/or prime minister, rather than specific ministerial portfolios. Such a department is present in many parliamentary democracies. The department is roughly equivalent in function to a president's office in a presidential system of government or an office of the council of ministers in a semi-presidential system.
In many countries, such a department is called a Prime Minister's Office. In some other countries, there is a Cabinet Office. In the United Kingdom, the Prime Minister's Office is a part of the Cabinet Office; in Australia and New Zealand, there is a single department called the Department of the Prime Minister and Cabinet. In some countries, such as Germany and Poland, the department supporting the prime minister (the Chancellor in Germany) is called the chancellery.
Self-governing states and provinces within federations that are parliamentary democracies often have similar departments, such as a premier's department or, in Australia, Department of the Premier and Cabinet.