The main role of the department is to support and advise the Taoiseach in carrying out various duties.

In addition, the Department of the Taoiseach is involved in a number of other areas such as the development and co-ordination of policy in relation to economic and social development (social partnership), Northern Ireland, the European Union and Oireachtas reform.

It also arranges State functions such as the annual National Day of Commemoration, presidential inaugurations, State dinners and provides a protocol service to the Taoiseach of the day.

[3] Under that act it was assigned:[4] the business, powers, authorities, duties and functions by the Constitution or by any existing or future Act of the Oireachtas or otherwise conferred on or to be discharged or performed by the Minister, who shall hold the office of and be styled Uachtarán na hArd-Chomhairle or (in English) the President of the Executive Council, and also the custody of and responsibility for all public archives and records and of papers and documents of State and of grants, deeds and other instruments of title relating to the property corporeal and incorporeal, real and personal for the time being vested in Saorstát Eireann and of records of the Executive Council and also the custody of the Seal of the Executive Council and also the responsibility for and control of the official publications of the Executive Council and also the administrative control of and responsibility for such public services and the business, powers, duties and functions thereof as may not for the time being be comprised in any of the Departments of State constituted by this Act.The position of Taoiseach was created under Articles 13.1 and 28.5 of the Constitution of Ireland, which was approved on 1 July 1937.

[5] Under the Constitution (Consequential Provisions) Act 1937, the Department of the President of the Executive Council was renamed as the Department of the Taoiseach from and after the coming into operation of the Constitution of Ireland, which occurred on 29 December 1937.