The budget of the Roman state varied greatly depending on the era. In general, the budget depended on the ratio of income and expenses. The worst situation was in the late imperial period, when Diocletian and Constantine the Great, tried to introduce “manual control”, e.g. setting the official prices of goods. As it turned out, the short-term positive results brought a later tragedy, because the empire lived on an eternal deficit.
Andy Goldsworthy in Caesar – Life of a Giant estimates the income of the republic’s treasury at 50 million denarii (200 million sesterces) before Pompey’s departure to the east. After his return (reorganization of the eastern provinces), the income increased to 135 million denarii. Caesar in 49 BCE imposed an exceptionally low tribute of 10 million denarii on Transalpine Gaul. Thus, at the time of the fall of the republic, the annual income of the Roman state was 145 million denarii. It is worth noting that in Rome you could live on 2-3 sesterces a day, where the cost of a tenement house was on average 60,000 sesterces, and the most magnificent properties could be bought for 2-20 million sesterces.
On this basis, mentioning the creation of several additional provinces in Egypt, Mauritania, Cappadocia, the Danube area, Dacia, Britain and others, it is possible to estimate the revenues to the budget of the Roman Empire around 125 CE at about 210-250 million denarii.
In 150 CE the state treasury had an income of 40,000 Roman pounds of gold, i.e. over 12,000 kg, and 18,000 pounds of silver, i.e. over 6,000 kg. This income consisted of contributions collected from conquered countries, then spoils of war, taxes and customs revenues from the provinces, and income from the exploitation of gold and silver mines in Spain, Macedonia and the Alps.
The empire’s budget was largely based on the spoils of war, taxes on trade and production, especially agriculture. Initially, they were relatively low, with considerable income coming from wars (along with free labour). Later, with the rise of the great latifundia, there were temptations to abstain from taxation. Hence the huge corruption in the exemption from tributes and the poverty of the already poor masses, had to cover the difference. Because from about the end of the 3rd century CE. plunder ceased to flow (the period of offensive campaigns was practically over), and the number of slaves decreased, the empire’s budget was characterized by a chronic deficit. The shrinking of the labour force reduced tax revenues, which were supplemented by tax increases.
The empire’s income also largely came from fees for entering the state, i.e. crossing the limes by neighbours from outside, e.g. Celts or other barbarians, not only for military defence. Income also came from trade. For example, on the Silk Road through Roman negotiatores sold goods only produced in the empire.
Around 400 CE the total income of the Empire was to be 300,000 pounds of gold, of which the eastern part was 270,000 and the western 30,000. This is what M. Wilczyński says in the book Germans in the service of the Western Romans in the 5th century AD
Compared to the period of the principate, there was an undoubtedly radical increase in the tax burden in the Dominator. direct taxes appeared for the first time (previously individual provinces paid a lump sum):
- under Diocletian land tax (capitatio iugutum), agricultural produce and industrial tools.
- under Constantine the Great a tax on municipal capitals (chrysargyron) and a tax on senators (follis). Chryzargyron was a tax paid in gold or silver every five years, transferred to the state treasury (sacrarum largitionum) every four years. It was first collected in 315 CE, although the introduction of similar taxation can be seen under Caligula. Artisans and merchants, persons profiting from loans, associations, and clubs, as well as prostitutes and harlots were subject to it. It included free people and slaves. Although the tax was levied at long intervals, it was quite a burden for many families. Tax was abolished by emperor Anastasius I.
- annona tironicum, for exemption from conscription.