By the mid-18th century, the Irish tithe in kind was converted into a monetary tithe (known as the modus decimandi) that systematically produced relatively high tithing rates upon a poor harvest and shifted the revenue risks borne by the clergy to tillage farmers. But this added risk burden – best exemplified by high tithing rates rel- ative to harvest revenues – only served to reinvigorate the groundswell of protest and violence that accompanied the many regional food riots provoked by a series of devastating harvests which, in turn, had created a subsistence crisis and the potential threat of famine. Taking the form of a secret society, these newest protestors – the “banditti” – took direct aim at the tithe, intervening by setting much lower rates backed up by violence (mostly against tithe agents). In 1823, Parliament responded to these disturbances by revamping the tithe in favour of a “composition”, making it com- pulsory only from 1832. However, the enactment of the mandatory provision triggered renewed protests and violence and the ensuing conflicts escalated into what became known as the Irish Tithe War of 1831-1838. This paper examines the tithing rates of the modus decimandi regime in terms of its share of annual crop revenues under different harvest scenarios and estimates the potential added revenue risks borne by tillage farmers under both monetary tithe regimes. This investigation finds that the primary cause of these se- cret society tithe disturbances, like that of the Irish Tithe War, was an increase in revenue risk that fell harshly upon small tillage farm- ers and for which there was insufficient compensation