Game concept
Suzerain Taxes
From the game's encyclopedia
Your Suzerain Taxes are the Taxes that you must pay to your Suzerain as part of your Obligations.
From your Suzerain's point of view, these same taxes are instead called Tributary Taxes to distinguish them from any taxes they may owe to their own Suzerain.
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.
Suzerain Taxes is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Your Suzerain Taxes are the Taxes that you must pay to your Suzerain as part of your Obligations." It is part of Taxes. Patch 1.20.1.2, from game/common/game_concepts/mpo_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/mpo_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.