Revenue stamps of Northern Ireland
Upon the partition of Ireland in 1921, separate revenue stamps began to be issued for both Northern Ireland and Southern Ireland. The latter were withdrawn soon afterwards upon the establishment of the Provisional Government, but the former continued to issue revenue stamps until the late 20th century. The need for separate issues for Northern Ireland came about since taxes raised there were meant to remain in the country. Most Northern Irish revenue stamps were British key types with appropriate inscriptions, but there were a number of different issues as well.
Partition of Ireland
The Government of Ireland Act 1920, which came into effect on 3 May 1921, provided for separate self-governing parliaments for Northern Ireland (the six northeastern counties) and Southern Ireland (the rest of the island), thus partitioning Ireland. While the parliament and governmental institutions for Northern Ireland were soon established, the election in the 26 counties returned an overwhelming majority of members giving their allegiance to Dáil Éireann and supporting the republican effort in the Irish War of Independence, thus rendering "Southern Ireland" dead in the water.