Age of Empires I and II Edit
All tributes made in Age of Empires and Age of Empires II have a 30% tribute tax: if a player sends 100 units of a resource, the recipient will receive 70 units. The tax has two purposes - first, it simulates how resources become lost on the way in the real-world due to corruption, bandits, tariffs, etc.
Second, it discourages players from giving huge amounts of resources to allies without any penalization. There are technologies at the Market which lower or even expunge the tribute tax, such as Coinage and Banking.
Purpose in Multiplayer Edit
In multiplayer, the most common use for tribute is to aid more resource-starved team players in bolstering their military or defense.
Purpose in Single Player Edit
In the single player campaign and skirmishes, neutral computer players may request resources in exchange for an alliance with the player; allied computer players may also request resources from the player in order to build up their forces. Players in turn may request resources from computers, who generally comply unless they have none to spare.
The manual for Age of Empires II also suggests sending tribute to enemy players in order to buy off an impending attack; this is ill-advised as sending tribute to enemies not only makes them stronger but also makes them more likely to attack regardless given the sudden influx of resources at hand.
Age of Mythology Edit
Similarly to the above-mentioned games, all tributes made have a tribute tax, but 10% rather than 30%.
Age of Empires III Edit
The player can have access to the ability to send Tributes to the Player Summary option of the in-game option, at the top right corner of the screen.
Once again, there is a tribute tax, 12% to be precise. This means that if a player has 300 Food and attempts to give a Tribute of 100 Food, they will instead lose 112 Food. This means that Tributes should be used in moderation, lest the player starves themselves trying to boost their allies.
This is even more important to keep in mind than in the other games, as there are no tax-reducing technologies, such as Coinage, that feature in Age of Empires III.