The Saladin tithe, or the Aid of 1188, was a tax, or more specifically a tallage, levied in England and to some extent in France in 1188, in response to the capture of Jerusalem by Saladin in 1187.
In July 1187, the Kingdom of Jerusalem's army was defeated by Saladin at the Battle of Hattin, and in October Saladin captured Jerusalem itself. When news of this reached Europe at the end of the year, a new crusade was promulgated. In January 1188, Henry II of England and Philip II of France discussed the crusade at Le Mans, with Joscius, Archbishop of Tyre in attendance, and on February 11, Henry began to organize the preaching of the crusade in England at Geddington. There he also discussed the "Saladin tithe."
It was a literal tithe of 10% on revenues and movable properties. The tithe was assessed by dioceses, rather than by shires, and local sheriffs had no role in collection of the tithe. The money was collected instead by the local priest or bishop, the dean of the local church, the local baron, and a sergeant of the king, as well as, notably, a Knight Templar and a Knight Hospitaller, whose orders were especially concerned with the defense of the Holy Land. Assessments were made by oaths in rural areas, and by a jury in urban areas. Certain items were exempt from assessment:
Anyone who joined the crusade was exempt from the tithe altogether. This was meant to encourage participation, and many did indeed join in order to avoid the tallage. All other landowners, both clerics and laymen, had to pay; if anyone disagreed with the assessment of their property, they were imprisoned or excommunicated. While taxes were usually collected by the Exchequer, a separate office with ten tellers was set up to collect the tithe in Salisbury.