Game concept
Subject Obligations
The game also links it as Obligations, Obligation.
From the game's encyclopedia
Subject Obligations define how much Tax and how many Levies a Subject provides to their Suzerain. A Subject's Government Form determines how their Obligations are modified.
For example, Feudal and Clan Vassals Obligations depend on their Vassal Contract, Administrative Vassal's depend on their Province Administration, while Tributary's depend on their Tributary Contract.
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Subject Obligations is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Subject Obligations define how much Tax and how many Levies a Subject provides to their Suzerain." The game also links it as Obligations and Obligation. Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.