The Irish Free State (Agreement) Act 1922 (12 & 13 Geo. 5. c. 4) was an act of the British Parliament passed on 31 March 1922. It gave the force of law to the Anglo-Irish Treaty, which was scheduled to the Act.
Section 1(1) of the act provides that:
Section 1(2) provided that for the purposes of giving effect to article 17 of the treaty:
Sections 11 and 12 provided for the right of Northern Ireland to opt out of the new dominion and remain within the United Kingdom.
Notably, the act (under section 1(5) of the act) was stated explicitly not to be the act of Parliament for the ratification of the Anglo-Irish Treaty. That function was to fall to the Irish Free State Constitution Act 1922. Instead, the Act was primarily intended to provide interim provisional arrangements necessary before the establishment of the Irish Free State, which under the Treaty had to be established on or before 6 December 1922.
By Order in Council under the act, the British Government formally transferred powers to the existing Provisional Government on 1 April 1922. That government had constituted itself on 14 January 1922 and had since chosen Michael Collins as its chairman. Their ministerial appointments now became official and were announced in Iris Oifigiúil No.19 of 4 April 1922.
The Irish Free State (Agreement) Act 1922 and the Irish Free State Constitution Act 1922 were repealed by the Statute Law (Repeals) Act 1989, Schedule 1, Part III.