What term refers to the tax placed on knights who sought to buy out of military service?

The term that refers to the tax placed on knights who sought to buy out of military service is scutage. In feudal society, knights were obligated to provide military service to their lords in exchange for land and protection. However, if a knight wished to avoid military duty, they could pay a tax known as scutage, effectively allowing them to buy their way out of service. This system was significant in developing feudal relationships, as it provided flexibility for knights and lords, while also generating revenue for the lord.

Vassalage describes the relationship between a vassal and a lord, characterized by mutual obligations, but does not specifically refer to the tax for military service. Fealty refers to the loyalty and allegiance a vassal owes their lord but is also not a financial term. Levy is a broader term related to the raising of troops or taxes in general, but it does not specifically denote the tax on knights seeking to escape military obligations. Thus, scutage is the precise term for this practice within the context of feudalism.