Luigi Einaudi was appointed a National Consultant by decree of the Lieutenancy on 22 September 1945, in recognition of his status as an anti-Fascist senator designated prior to 28 October 1922 and his active opposition to the regime after 3 January 1925. The categories from which the government selected consultants, as stipulated by the Lieutenancy’s legislative decree of 30 April 1945, included trade union organisations, veterans, representatives from the cultural sphere, the liberal professions, technical executives, and former anti-Fascist parliamentarians. Additionally, members were drawn from the six constituent parties of the National Liberation Committee, the Italian Democratic Party, the Republican Party, and the Liberal Democratic Concentration, which were not part of the National Liberation Committee. Individuals who had served as ministers, undersecretaries, as well as High Commissioners in the governments established after the liberation of Rome were also included in the Consulta.

According to the provisions of the Lieutenancy Decree of 5 April 1945, the Consulta was mandated to provide opinions—compulsory for draft budgets, state accounts, taxes, and electoral laws—on general matters and legislative measures presented by the government. Composed of ten Commissions, the Consulta operated from 25 September 1945 to 10 June 1946. Einaudi served as a member of the Finance and Treasury Commission during this period.

Following his election to the Constituent Assembly, Einaudi participated in the deliberations of the Second Sub-Commission of the Commission for the Constitution—colloquially referred to as the "Seventy-Five"—which was tasked with preparing a draft Constitution for submission to the Constituent Assembly. The Second Sub-Commission was responsible for defining the constitutional framework of the Republic. Einaudi was an active member from its inception on 23 July 1946 until 31 May 1947, when he was appointed Minister of Finance and the Treasury. During his tenure within the Sub-Commission and in plenary sessions of the Constituent Assembly, Einaudi made significant contributions about the representation of intermediary bodies in the Second Chamber, trade union legislation, the form of government, local autonomy, referenda, the Constitutional Court, the electoral system, education policy, monopolies, savings, land reform addressing latifundia, the relationship between the State and the Catholic Church, special regional statutes, and the Paris Peace Treaty.