In the July/August 2014 issue of BAR, author Nathan T. Elkins compares archaeology to a crime scene investigation. When looters remove coins from a site, they take away the “smoking guns,” the definitive evidence. Read more >> 
Under Domitian (emperor from 81 to 96 C.E.), the Fiscus Iudaicus was administered very harshly, and there was no shortage of informers (Suetonius, Domitian 12.1–2). In particular, new victims of the tax were non-Jews who “lived a Jewish life without publicly acknowledging that fact” (i.e., Jewish sympathizers and gentile Christians) and Jews who “concealed their origin and did not pay the tribute levied upon their people” (i.e., apostate Jews and Jewish Christians). Dio (67.14.1–2) records that Domitian had the consul, Flavius Clemens, and several others killed in 95 C.E. on account of a charge of atheism; this was a charge that condemned others who “drifted into Jewish ways.” Although some of the accused escaped execution, the property of all was confiscated by the state.
The coins of Nerva have sometimes been interpreted as evidence of the abolition or partial repeal of the Fiscus Iudaicus by him.2  But a strong case can be made that the coins instead celebrated a reform of the tax rather than its abolition. After all, ostraca from Egypt indicate that Jews there paid the tax at least through Trajan’s reign (98–117 C.E.).3  The meaning of the coin can be sharpened as referring to the charge of atheism and the harsh prosecutions that resulted in death and/or the confiscation of property of that second group of people prosecuted by the tax under Domitian: Jewish sympathizers and gentile Christians, as these appear to have been the new victims in Domitian’s reign.4 
When Nerva came to power, he sought to bring an end to the excesses of Domitian’s reign and represented his predecessor as a tyrant. This is readily apparent on Nerva’s other coins, the most conspicuous, of course, are his gold, silver and bronze coins that bear an image of Libertas (Liberty) holding a rod and the cap of freed slave, both of which are implements used in the Roman ceremony to free slaves; the implied message of the imagery is that the Roman people are now freed from Domitian.
One of Nerva’s specific reforms—celebrated by the Fiscus Iudaicus coins—was to forbid people from accusing others of leading a Jewish life (Dio 68.1.2). As Heemstra argues, the consequence of Nerva’s reform means that the Roman state prosecuted the tax under a purely religious definition of Judaism, rather than ethnic one. And it was Nerva’s reform of the tax that led to sharper distinctions between Jew and Christian.
I am presently engaged in the research of Nerva’s coinage program. In particular, I am interested in the frequency of various images on his coinage and the audiences at which those images were targeted. Out of a sample of 408 sestertii from hoards and excavations from Rome, Italy, England, France, Germany, Austria, Switzerland, Luxembourg, the Netherlands, Slovenia, Croatia, Hungary and Romania, there are only 13 examples of the Fiscus Iudaicus sestertii. In other words, they are only 3.19% of the sestertii. And although the Fiscus Iudaicus types are not known from excavated finds in Rome and Italy in the samples I have consulted, they do abound in museum collections in Italy, formed centuries ago, probably from local finds, which is suggestive evidence that the imagery was targeted at the urban audience of Rome, and probably the nobles. It was evidently the wealthy and politically powerful class of Roman elite who had been subjected to the expanded abuses of this tax under Domitian, as informers stood to receive part of the proceeds after a successful trial, and accusation was also an expedient way to harm one’s political enemies.
There is some irony in the fact that Nerva’s Fiscus Iudaicus coinage, celebrating his reforms, was produced in small numbers and targeted a small segment of the Roman population, although the ultimate result of his reform was the growing distinction between Jew and Christian. It is now a distinction that billions of people today take for granted.
New from BAS: Partings—How Judaism and Christianity Became Two . Never before has this multi-faceted process been documented so engagingly and so authoritatively by so many eminent scholars. Read more >> 
Nathan T. Elkins is assistant professor of art history  (Greek and Roman art) at Baylor University. He is the staff numismatist at the excavations of the Roman/Byzantine synagogue at Huqoq in Israel. His primary research interests include Roman imperial coin iconography and political communication, as well as the illicit trade in antiquities. Follow him on Academia.edu .
1  On the meaning of the legend in general, see M. Goodman, “The Meaning of ‘Fisci Iudaici Calumnia Sublata’ on the Coinage of Nerva,” in S.J.D. Cohen and J.J. Schwartz, eds., Studies in Josephus and the Varieties of Ancient Judaism (Leiden and Boston: Brill, 2007), pp. 81–89. For the translation used here, see M. Heemstra, “The Interpretation and Wider Context of Nerva’s Fiscus Judaicus Sestertius,” in D.M. Jacobsen, and N. Kokkinos, eds., Judaea and Rome in Coins, 65 BCE–135 CE (London: Spink and Son Ltd., 2012), pp. 187–201.
4  Heemstra, “Nerva’s Fiscus Judaicus Sestertius,” pp. 189-195; Heemstra, The Fiscus Judaicus, pp. 32–66.
*Correction, June 26, 2014: This post originally associated non-Jews who “lived a Jewish life without publicly acknowledging that fact” with apostate Jews and Jewish Christians, and Jews who “concealed their origin and did not pay the tribute levied upon their people” with Jewish sympathizers and gentile Christians.