The bounty is a tradition within the Imperial Legions, in which soldiers of different rank levels are provided with remuneration in the form of loot from their destroyed enemies, as well as a direct reward for certain achievements. The rewards vary based on rank, and on who their commanding officer is, but all Imperials Legions work on the concept of the bounty. It is through the bounty that soldiers can become relatively wealthy, and it spurs them on to greater feats of heroism and martial prowess.
The Bounty began with the early Imperial Legions following the defeat of the last of the Daemon minions of the Dark Prince Aloth. The Empire had not fully exhausted it's list of enemies, and needed to retain the experienced and battle-hardened veterans that they had in their armies. However, many soldiers had joined to defeat Daemons, not to crush rebellions or establish frontier colonies. In order to keep these soldiers in the ranks, the first bounties were instituted. The rewards began with promises of land in the newly conquered or re-conquered lands, eventually expanding to rewards for battlefield feats as well (1 Silver Piece for each enemy shield recovered, or 10 Gold Pieces for the first soldier over the walls in a siege). The tradition was not without even earlier roots though, as soldiers of the holy armies of the Second Age were given rewards for each daemon-spawn defeated, using the distinctive horns or talons of daemonic creatures as their proof.
All soldiers of Imperial Legions will generally have some way to take advantage of the bounties, depending on who their direct superior is. All bounty comes from the Emperor themselves, as they are considered to be the owner of whatever the army loots or gains as a result of the war. The Emperor has traditionally yielded all but loot that is "directly impactful to the security, harmony, or prosperity of the realm" to the army that gained it (an example of such exceptional items could be magical items of great power, or items of great symbolic significance such as the personal banner of a rebel general or leader). Generals will set the bounty conditions for their Legates, who will set their bounty conditions for the Centurions, and Centurions set the conditions for everyone below them. As such, all bounty is usually centralized with the general's administrative staff, and then handed back down the chain to all of those that have earned it. This acts as a system of remuneration for the officers of the army as well.
It is traditional for bounties to be paid out no later than within 1 week of the action that earned it. Lateness in paying out bounties has in a number of cases in the past led to small-scale mutinies, as soldiers who were owed a particularly high amount would refuse to go on until their account had been settled. It is because of this the current-day Imperial Legions are meticulous and expedient in providing the soldiers with their bounties, especially the common ones who have no political future to lose.