Why did Diocletian extend land taxation to Italy?

Diocletian extended land taxation to Italy primarily to secure the necessary funds to support his extensive domestic and military reforms.1

Following a period of severe political and economic instability that brought the empire to the brink of collapse, Diocletian implemented a program of reorganization to restore imperial strength. These policies—which included increasing troop strength, reorganizing the army, and expanding the bureaucracy—were extremely expensive. Additionally, the empire faced the legacy of a precarious financial situation characterized by long-term inflation.12

To address these fiscal demands, Diocletian instituted a new, systematic tax structure based on the jugum (a unit of cultivable land) and the capitatio (a tax on individuals). By extending this land taxation to Italy, which had previously been exempt, Diocletian aimed to ensure a reliable and consistent stream of revenue to maintain the state's administrative and military functions.1