To allow a portable body such as a microcircuit card to be used for executing an informal transaction according to the history of past financial transactions.

This informal transaction consists of a) a stage for investigating the range of transactions carried out after the date of a final informal transaction, b) a stage for investigating various transactions carried out after the final informal transaction found at the stage a) in the history, c) a stage for using means including servers (TEPT, CAR) connected to terminals (12, 14; 16) for calculating the amount of money of a next informal transaction, d) a stage for transmitting a remittance instruction for a 3rd person as a recipient, and e) a stage for updating recorded information. Preferably, the next informal transaction is the format of a marker which has its format written in an area as the format of a financial area and has a date area including the date of a current informal transaction and the financial value area including a value which is not financially important and specially zero.