Origin and History of the Surname Cash
"This interesting surname recorded as Cass, Casse, Cassie, Cassey, Cassy and in Dublin (Ireland) as Cash, can be English, Irish or Scottish.
It is of the group of surnames which derive from medieval personal names, Cass or Cassie being a nickname form of the popular female name 'Cassandra', a Greek name meaning 'snarer of men'. It was introduced into Europe at the time of the famous crusades of the 12th century.
It is said that the first Cassandra was a Trojan prophetess of classical legend, who was condemned to foretell the future, but never to be believed! For whatever reason, this story was widely popular in medieval times.
The name is a metronomic, which is so say that it derives from the mother's name, rather than the father's. The personal name appears as Casse Rumpe in the Hundred Rolls of Cambridge in 1279, whilst William Casse was mentioned in the pipe rolls of Essex in the year 1300. Other recordings include Elyzabeth Casye, who married William Kendricke at St Dionis Backchurch, London, on August 27th 1564, whilst John Cass of Dalkeith, Scotland was summoned before the Privy Council for Scotland in 1566, and James Cash is recorded in Dublin in 1772. The first recorded spelling of the family name is shown to be that of Roger Cass, which was dated 1130, in the Registrum de Dunfermelyn, during the reign of King David 1st of Scotland, 1124 - 1153.
Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to 'develop' often leading to astonishing variants of the original spelling." Source