On 25 June a fifth emergency tax was introduced to cover the increased expense. This was the Tricesimation which was the ducal answer to the estates’ Accise. For the first time the duke had a tax that both approximated to the level of economic production and above all was under his control.⁷⁷ ⁷⁷ The Tricesimation was a one-thirtieth purchase and produce tax collected by ducal officials…. No records of the level collected survive, but around 1700 the Tricesimation brought in about 100,000fl. annually.
Source: wiktionary