Imperial Tithe

"In this world nothing can be said to be certain, except death and taxes."

– Benjamin Franklin

In the grim darkness of the far future, feudalism is back in style with the Imperial Tithe. No doubt the irony of coming full circle was not lost on the Emperor.

As the Emperor of Mankind was preparing the Great Crusade, he realized that while the Legiones Astartes were excellent as the "spear tip", or vanguard troops, a spear tip still needed a wooden staff to support it. In other words, he needed regular humans to support the Legions. And while Terra alone had billions, the galaxy is a big place, and they couldn't hold every world with just Terran armies (ironically, considering how tiny the numbers involved in 30K and 40K wars are, they might actually have been able to hold the galaxy with just Terra's armies- but then again that might just be GW having no sense of scale). To get around this, the Emperor imposed the Imperial Tithe, a set of payments that a compliant world must pay to the Adeptus Terra for continued protection. For this, an Imperial Commander, or Planetary Governor, must give the Imperium of Man not monetary taxes, but the following:

1. They must pay a tithe of manpower in regiments for the Imperial Army, and later the Imperial Guard.
2. They must provide goods for warfare, such as food, weapons, vehicles, or minerals to make any of the above.
3. They must provide the league of Black Ships with all the unsanctioned-psykers that the planet has managed to capture.

Monetary taxes are officially separate from the Imperial Tithe, and weren't added until much later when the Emperor retired to Terra and Malcador the Sigillite took over the Council of Terra. Horus Lupercal, Primarch of the Luna Wolves, had concerns that the taxes could end up raising rebellions on planets. In the following ten thousand years, payment of the Imperial Tithe has resulted in planets declaring rebellion, but these in turn are crushed with extreme prejudice. Governers who engage in tax evasion tend to be have brief encounters with the agents of the Officio Assassinorum.

This said, the tithe system isn't utterly one-sided. Planets also receive goods from the Imperium to better serve it (ingots of metal for Lasgun Manufactoria, Space Potatoes to feed Lasgun Manufactorium workers, etc) and some more to keep at least the local elites happy. "The Emperor Protects and The Emperor Provides". Despite the high burden of an "Exactis Extremis" designation (the highest conventional tithe level), many worlds would prefer to keep it as this means that the Imperium will in turn invest resources into the planet and ensure that it is protected. Having their status downgraded is rarely good and if it drops low enough, the Imperium functionally cuts the planet loose and forgets about it - why bother investing or protecting something that isn't useful. Then again, one of the most common causes of rebellion in the Imperium is the tithe rating of a world being jacked up to levels that would require conscripting every single viable citizen, enslaving the entire population for labour and having children work the moment they can walk. Occasionally all 3 at once, because the Administratum rarely sees these things as mutually exclusive or as a cause for concern.

As far as the Adeptus Terra is concerned, there are two big exceptions to the Tithe that are systematically classed as "Aptus Non": Space Marine homeworlds and Adeptus Mechanicus Forge Worlds. On paper, they are completely exempt from the regular Imperial Tithe. In practice, however, it is a little more complicated:

• Space Marine Chapters, besides, you know, being super-soldiers fighting the Emperor's wars; must provide 5% of all their gene-seed to the Adeptus Terra. Said gene-seed is turned over to the Adeptus Mechanicus for testing to make sure that the Chapter's is stable and free of taint, to be used as emergency reserve should the Chapter get mauled or to be called upon if a new Founding of Space Marine Chapters is decided. Any further contribution to the Imperium wars and/or economy is made on a purely voluntarily basis.
• Adeptus Mechanicus Forge Worlds are individually free of the Tithe, but the Adeptus Mechanicus as a whole is still bound by the Treaty of Mars. Practically this translates in the Forge Worlds periodically sending huge shipping of weapons, tanks and other materiel to the Departmento Munitorum and starships to the Imperial Navy, along with enough Enginseers to keep everything running. The Forge Worlds also 'tithe' their psykers to the Black Ships when one cruises along, albeit this is more of an easy way for the Mechanicus to get rid of them. The treaty means that the Mechanicus will build anything the Imperium wants in exchange for the resources needed to do so. There's a lot bad with the Machine Cult, but the best of the good parts is that they don't really care about profit so much as keeping their forge-temples constantly producing in worship to the Machine God.

Real World Parallels

The most direct parallel from the Imperial Tithe and Real World history would be the operation of economies in the Bronze Age. In that system there was a class of scribes and bureaucrats employed by the state which took and kept track of what was produced and allocated it to various people so it could be used to achieve various tasks. Peasants farmed, provided a percentage of their crop to the state who used it feed artisans who made tools, cloth, beer and similar, which was taken by the government and provided to various peasants, who'd also spend some time working in mines or clay pits and working on large scale irrigation projects. Raising Troops worked along a similar line. How a group of peasants or artisans was to get the job done was broadly a matter for them to sort things out, as long as they met or exceeded their quotas was all that the scribes in the palace cared about. The Inca Empire's Mit'a system is a pretty good parallel in many regards.

This was called paying taxes "in kind". That is, whatever you do for a living you pay a certain percentage of. Most of this was used by the local lords as a storage of goods to be used in case of emergency and food stores for lean times. Yes, it may be shocking but back then the lords and such actually did do their job properly. Amazing what can be accomplished when your personal wealth and power is dependent on keeping your subjects safe and prosperous.