The Department of An Taoiseach is the government department of the Irish prime minister, An Taoiseach (in the Irish language, the leader). It is based in Government Buildings, the headquarters of the Irish government, on Merrion Street in Dublin.
The Department was created in 1937 and replaced the Department of the President of the Executive Council, the department of the Irish prime minister under the previous prime ministerial title in the Irish Free State.
Both departments are descended from the Chief Secretary for Ireland's Office, originally based in Dublin Castle, which was the administrative office of the dominant politician of cabinet rank in the British government in Ireland in the nineteenth and early twentieth centuries.
The head of the Department of An Taoiseach (sometimes also written as the Department of the Taoiseach) is known as the Secretary-General of the Department.
The Taoiseach is appointed by the President upon the nomination of Dáil Éireann (the lower house of parliament), and must, while he or she remains in office, enjoy the confidence of the Dáil.
The Taoiseach nominates the remaining members of the Government, who are then, with the consent of the Dáil, appointed by the President.
The modern position of Taoiseach was established by the 1937 Constitution of Ireland, to replace the position of President of the Executive Council of the 1922-1937 Irish Free State.