An indiction (Latin: indictio, impost) was a periodic reassessment of taxation in the Roman Empire which took place every fifteen years.
Indictions originally referred to the periodic reassessment for an agricultural or land tax in the Roman Empire.
Changes to the tax system usually took place at the beginning of one of these cycles and at the end of the indiction Emperors often chose to forgive any arrears.
[5] At the start of the next indiction in 118 AD, Hadrian wrote off 900,000,000 sesterces of tax arrears, which he refers to in an inscription as the largest remission ever granted.
[12] The first evidence is an edict by Marcus Mettius Rufus, the Prefect of Egypt in AD 89, requiring property and loans to be registered.
In 537 AD, Justinian decreed that all dates must include the indiction via Novella 47,[18] which eventually caused the Byzantine year to begin on September 1.
[clarification needed] But in the western Mediterranean, its first day was September 24 according to Bede, or the following December 25 or January 1, called the papal indiction.