This article examines one widespread but widely overlooked informal party practice to access state resources indirectly: the ‘taxing’ of MP salaries, which obliges candidates who win elected office on a party ticket to regularly donate a fixed share of their private income to party coffers. Linking Duverger’s classical approach on party organization that stresses the importance of party–society relations with the more recent, highly influential cartel party theory that argues that parties are shaped by their relationship with the state, we specify factors that shape the acceptability of this informal practice and thus parties’ capacity to extract rent from their MPs. The analysis of an original dataset covering parties across a wide range of advanced democracies reveals that demanding salary transfers from national MPs to their parties are not only more common in leftist parties as argued by Duverger but also in systems in which the penetration of the state apparatus by political parties is intense as argued by the cartel party approach. Linking the two perspectives further reveals that ideological differences between parties shape their relative capacity to collect higher payments from MPs in systems where parties and the state are less intertwined.