Context: In May 1922 the British Government with the agreement of the Irish Provisional Government established a commission chaired by Lord Shaw of Dunfermline to examine compensation claims for material damage caused between 21 January 1919 and 11 July 1921. The Irish Free State's Damage To Property  Act, 1923 provided that only the Shaw Commission, and not the Criminal Injury Acts, could be used to claim compensation. Originally, the British government paid claims from unionists and the Irish government those from nationalists; claims from "neutral" parties were shared. After the 1925 collapse of the Irish Boundary Commission, the UK, Free State and Northern Ireland governments negotiated revisions to the 1921 treaty; the Free State stopped contributing to the servicing of the UK national debt, but took over full responsibility for compensation for war damage, with the fund increased by 10% in 1926. The "Compensation  Commission" worked until March 1926, processing thousands of claims.

Question: When was the treaty revised?

Answer: