Our main research interest lies in the realm of Persian influence brought by Umayyad occupation and government in the Iberian Peninsula, especially in the area of Catalonia in the period spanning between the seventh and eleventh centuries. In this area, successive political rulers—Visigothic, Islamic, Carolingian and, finally, Catalan—relied on a wide range of taxes and a varied spectrum of fiscal procedures. Fiscal systems were intimately tied to the peculiarities of the political power or social organization they served. However, when political regimes changed, not always homogenously, the result was a cumulative stratigraphy of taxes. Our purpose is to underline the evidence for the common use of the fiscal term “tasca” in late Latin private documents from this area, and to sugest its correspondance with the Sassanid taxation concept of "tasq". As historiography has proven, the Persian practice of the tasq payement was borrowed by early Umayyad administration in the Jazirah and Sawad, and considered as a general rate of kharaj in early Islamic administrative practices. We will evaluate the coincidence, phonetic and semantic, of the Catalan word "tasca," occuring in Carolingian and Catalan documents with the term tasq, as used under Sassanian rule, and registered in the first agreements of kharaj elaborated by the earliest administrative Islamic tradition. We suggest that the etymology of the Catalan word arises from ancient roots recorded in Persian fiscal contexts. We sugest, too, that the word was introduced simultaneously with introduction of the Islamic practice of kharaj after the Umayyad conquest of the Northern areas of the Iberian Peninsula. In conclusion, we will suggest that this unexplored example is suggestive of broader possibilties of cultural transfter from East to West with the expansion of Muslim rule. It is also interesting to note that the Catalan word tasca was use to refer to taxation practices in the Pyrenees until the eighteenth century and is still used in the Catalan language to refer to a job, duty or obligation.