S'mon said:As Gizmo has noted, a medieval setting does not have the ability to levy sales tax or income tax. Taxes will be property taxes levied annually, duties on imports & exports through the city gates & docks (I hit the PCs with that when they brought some chain shirts into town to sell)and requirements for feudal service. Some modern taxes could also work, eg Inheritance Tax on the wealthy (unlikely in a feudal society) and Stamp Duty on the sale of land & buildings. Medieval towns had a narrow tax base, most tax came from a small number of property owners - burghers - who were also usually the only people counted as real 'citizens'.
Inheritance Tax was definitely a feature of medieval/manorial life and was far from being restricted to the wealthy. Peasants taking possession of a parcel of land paid entry fees (gersum) and upon the death of a villein, the lord collected a death duty (heriot or "best beast", meaning the lord usually took the villein's best farm animal or a like amount of goods in payment).
I think some of these ideas being thrown around are very much mixing Renaissance concepts into the Medieval/Feudal model. In Medieval times, the vast majority of "income" came from villages, not towns. Towns didn't develop as significant economic centers until well into the late medieval period and villages didn't start to die out until several hundred years after the beginning of the Renaissance period. In addition, the idea of taxes on trade (i.e. import duties, etc.) during the Feudal period is somewhat erroneous as well, since most trade at that time was conducted not by private individuals but by powerful land-owning nobles (the only ones with enough excess to make trade worthwhile) who obviously wouldn't be taxing themselves. It's important to remember that the Feudal system was based almost exclusively on the exchange of services and land; not money and goods as a form of payment. Kings granted land to Counts, Dukes and Barons in exchange for their provision of trained military personnel. The greater nobles then obtained those soldiers by granting sub-plots of their land to knights/lords in the form of a manor, who financed their living and military equipment by granting sub-plots of their manor to serfs, who paid for that by rendering service back to the lord in the form of labor on his own lands. This was, by a large margin, the major form of "commerce". Any exchange of money or goods was in extremely small quantities and usually localized to a very small area. In fact, it was the rise of trade which essentially brought about the end of the Feudal period (by creating means of exchange other than service which were more attractive and beneficial to the parties involved).