The authors agree that the surname presents multiple etymological possibilities. The first refers to a name of Germanic origin, Tasso or Taso, documented from the first decades of the 8th century in central-northern Italy and linked to the Lombard tradition; these are hypocoristics of names compounded with the element Tas(s)o-, such as Tassimanno, Tassimundo or Tassiperto. The second possibility connects the surname with place names formed from tasso as the name of a plant, among them Tasso —locatable in zones of Genoa, Mantua and Arezzo—, Tassano and Tassani. Finally, in very isolated cases, it could reflect a nickname derived from tasso in the sense of badger.

E. De Felice specifies the regional distribution of the different variants: Tasso predominates in Liguria; Tassi, Tassoni and Tassinari are concentrated in Emilia-Romagna; and forms such as Tassello, Tassin or Tasin, Tasinato and Tassoni are typical of the north-east of Italy, in the regions of Veneto, Friuli-Venezia Giulia and Trentino-Alto Adige.