Since the first postal convention between the Kingdom of Sardinia and Austria came into force in June 1844, which allowed letters to be paid at destination or sent totally assigned, the rules for the taxation of insufficiently franked letters were always expressed clearly and the method of taxation underwent various changes between the first convention that entered into force and the last, which lasted until the entry into the GPU of the two States. In the convention of 1844 and the later one of 1853, letters with insufficient postage were taxed on arrival as if they were unfranked with complete loss of the value of the applied stamps. After the interruption of communications between the two States due to the Second Italian War of Independence, at the resumption of postal relations in September 1859, the letters were franked only up to the respective border and taxed for the journey in the State of destination. With the resumption of the convention on May 15, 1862, insufficient postage was still taxed as unfranked but only until September 1862; from 1 October 1862 the value of the stamps applied on insufficient letters was accounted in the taxation applied on arrival. Finally, with the entry into force of the agreement of 1 October 1867, unfranked letters paid a higher amount than franked ones and the taxation for insufficient letters was calculated with respect to the postage of unfranked letters.

Rechts: Unzureichend frankierter Brief der zweiten Gewichtsstufe aus Pavia mit Nachgebühr.