Broadly speaking the Roman state in its mature form accounted for two types of taxation, the vectigal and tribute. While vectigalia was often used as a synonym for the state's revenues as a whole it in fact describes specifically the revenue collected from rents on public lands and possessions and the profits gained from such property. It also describes importation duties, taxes on wills, and other indirect taxation. As such the vectigal only was collected from individuals participating in such activities. Tribute was the direct form of taxation paid by the individual to the Roman state. As of 167 it was no longer levied on citizens. Provincial tribute varied according to the province. Some provinces paid fixed sums. Gaul, for example, paid a fixed yearly sum of 40 million sesterces. In other provinces (e.g. Asia) provincial tribute was paid as a fraction (usually a tenth) of the grain harvest, which was then sold by the state. Provincial tribute was therefore raised on a provincial basis (usually in grain rather than cash), not necessarily individually. The state leased out contracts for the collection of the vectigal and tribute to publicans, who bid a certain amount to the state in advance and were allowed to keep the surplus. The result is that provincial taxation laws were often in flux, and the "real" taxation was usually greatly in excess of the money paid to the state. Publicans also need not necessarily follow any pattern in collecting the tribute. While collection of the vectigal was relatively straightforward (you just collect a certain percentage of various activities) in theory a publican could force a single individual to pay out the entirety of his bid (provided this dude was rich enough). To add to the problem, provincial governors were able to levy extraordinary duties on the provinces in order to maintain their military forces--one famous method of extortion was to levy extra grain taxes in excess of the amount needed to feed the army and then sell the surplus at a premium.

Augustus massively reformed tax administration in the provinces. In the Principate tribute was no longer collected by publicans, who were relegated to collection of the vectigal. Instead, the census was extended to the provinces and local magistrates became responsible for the collection of tribute, which increasingly became an individual affair rather than a duty levied on the entire province. How exactly the provincial paid his tribute and what amount he paid depended on the province. I'm not too sure about Judaea, but in Syria, for example, men above the age of 14 and women above the age of 12 were responsible for an individual tribute (in addition to the province's tribute as a whole), although I don't know if we know by how much (almost certainly a fixed sum). Despite these reforms, of course, tribute in the Principate was not necessarily so straightforward. Provincial procurators had just as many powers as the publicans had before them, and an unscrupulous procurator could cause a lot of damage, as the procurator of Britain did on the eve of the Iceni's revolt. The system was more centralized and more efficiently administrated, but the tribute of the provincials was still often in flux