The authors agree that the surname has notable presence in northern Italy, with areas in the Alessandria, Milan and Brescia areas, as well as in the Valtellina. E. Rossoni also notes that the variant Caratto is scarcer and peculiar to the Turin and Alessandria areas, and proposes that both forms could derive from a nickname based on the archaic word caratto, with the sense of "share" or "division". The first documented traces of its transformation into a surname go back to 1564 in Bergamo, with Cristoforo Caratti as Consul of the Merchants.

Rossoni adds that the form De Carate appears as early as the 13th century in Lovero, in the Sondrio area, with origin in Carate Urio, in the Como area. R. Brondolo, for his part, documents the surname from the 15th and 16th centuries in Lombardy, in the Swiss canton of Ticino and in Acqui Terme, and links all its branches to the Lombard place name Carate. Brondolo also specifies that the spelling with double t is documented from 1745.