Tithe Grade is a bureaucratic designation of the Adeptus Terra that determines the amount of raw materials, resources or soldiers an Imperial world must supply to the Administratum as taxes or tithes to keep the Imperium of Man's interstellar government functioning and to fill the ranks of the Imperial Guard or provide human psykers to the Black Ships of the Adeptus Astra Telepathica. The size and nature of the tithe depends on the type of world it is applied to, as a large Hive World like Necromunda will be expected to provide a much larger tithe than a pre-industrial Feudal World. A tithe can be any type of resource: food, weapons, minerals, manufactured goods, people, etc. Space Marine Chapter Homeworlds do not normally provide tithes to the Imperium since their resources are to be used to maintain the Space Marine Chapter that controls them, and are given the tithe grade Aptus Non. Agri-World tithes generally refer to how much of the planet's food production must be supplied to the Imperium.

Known Tithe Grades

The make-up of a given world's tithe payments, regardless of the size of those payments as indicated by the Tithe Grade, is determined by the section of the Administratum responsible for the overall governance of that world's Sector and sub-sector of space. The known Imperial Administratum Tithe Grades are listed as follows, from highest (most tithe required) to lowest (least tithe required):

• Exactis Extremis - the largest Tithe Grade
• Exactis Particular
• Exactis Prima
• Exactis Secundus
• Exactis Tertius
• Decuma Extremis
• Decuma Particular
• Decuma Prima
• Decuma Secundus
• Decuma Tertius
• Solutio Extremis
• Solutio Particular
• Solutio Prima
• Solutio Secundus
• Solutio Tertius
• Adeptus Non or Aptus Non - No tithe allowed due to past events like an Exterminatus or if the world is a Space Marine Chapter Homeworld

Sources

• Warhammer 40,000 Rulebook (3rd Edition), pp. 114–115