From time to time various emperors offered immunity, tax exemption and freedom to cities of the Imperial domains, these being privileges whose precise nature has not yet been established. Claudius, for instance, granted the island of Cos, birthplace of his personal doctor, immunity. During the year 52-3 A.D., so we learn from the historian Tacitus, exemption was granted to Ilium, Rhodes and Cos. The city of Elatea, in Phocis, enjoyed the privileges of freedom and immunity, while in Hadrian's reign Corinth was declared exempt.
Pliny the Elder records that twelve cities in the province of Asia were declared free and consequently independent of the provincial governor (legatus proconsule). But in real terms the freedom of these cities was not necessarily accompanied by their exemption from tax, even if when something like this happened it was looked on as a precious gift.
Lastly, the renewal of Delphi's and Minoa's freedom by successive emperors is an indication that privileges could probably be annulled by the refusal of an emperor to recognize his predecessor's decisions.

A brief but important change to the existing state of affairs in Hellenic cities occurred when in 67 A.D. Nero decided to have them declared free, a fact that meant they could govern themselves, and exempt. But this decision was revoked by Vespasian in 69 A.D., because of an outbreak of unrest, declaring that the Hellenes had forgotten how to be free.

Getting Roman citizenship - Roman citizen rights, in other words - did not entail immunity from taxation and liturgies. The Third Edict of Cyrene clearly shows that when an inhabitant of the provinces got Roman citizenship, he was not simultaneously to be released from paying taxes and taking on liturgies. Nevertheless, it is known that Augustus granted exemption to Roman doctors. Vespasian, too, decreed that a large group of citizens, including doctors, had the right to be exempt from tax. Exemption was a privilege also granted to Roman senators in the East; to famous athletes; to mariners; and to the Union of Artists of Dionysus, made up of a community of actors, poets, musicians, and singers giving performances the length and breadth of the Eastern Mediterranean.

Hadrian was fairly generous, releasing philosophers, orators, grammarians and doctors from liturgies, priestly rites, and having to pay army maintenance dues. But this decision of his, according to the statements of Antonin`us Pius are anything to go by, led to an outbreak of dangerous crises in the cities. He was indeed trying to restrict cases of exemption by setting a limit on the number of exempt from each profession in keeping with the size of every city which was to enjoy this privilege. As can be seen from the decrees of Hadrian, Antoninus Pius and Marcus Aurelius, the guild of charterers or dockers was ever ready to exploit the privilege of exemption so that its members should not have to pay any kind of tax or duty whatsoever.