Throughout the imperial period the structure of the senatorial career and the numbers of posts which senators might hold remained essentially what had been established by Augustus. Any changes which were made were relatively slight. Similarly, the increasingly common employment of men of non-senatorial origin in administrative posts had already been introduced in Augustus' reforms. This is well exemplified by the posts of the praefectus Aegypti, the two praefecti for the grain supply and the fire brigade in the city of Rome, together with the financial procurators, who performed various duties in both the imperial and public provinces. Further examples are the imperial freedmen and slaves, who, after the death of Augustus, could provide information on the financial health of the aerarium and the various imperial treasuries, for which they were responsible, as well as for outstanding taxes. Yet Augustus had only laid the foundations for this new style of government, which was largely alien to the Republic. It would not have been possible to foresee how the administration would expand and develop. In his biography of the first princes, Suetonius typically makes no reference to equestrian posts – that is, the new officials whose appointment foreshadowed what was to come – although he very carefully notes the new senatorial posts created by Augustus.

The degree and speed at which the non-senatorial areas of administration developed alongside those controlled by senators is still not entirely clear. The main reasons for this are, on the one hand, the way in which information has been passed down to us and, on the other, the fact that the duties of these posts were probably often not constituted through formal enactments, in particular those which would be recorded in the Senate.