The Red Book is one of the registers of the Paris Chamber of Accounts destroyed in 1737. With the help of various extracts and tables, Charles-Victor Langlois had been able, in 1916, to propose a detailed reconstruction; but the manuscript. 20506 of the National Library of France, which had remained unknown to it, adds many new elements to the investigation. In this way, it is possible to attempt a codicological reconstruction of the register, and above all to gain a better understanding of the very heterogeneous content. In total, the coins range from 1204 to 1338, but the core of the compilation consists of two parallel series: one recorded inheritance from the King of France from 1297 to 1321 and the other from 1301 to 1315 for life and will. The volume also contains documents not emanating from the King, including private acts and acts of royal precedence, which are genuine files on the fate of various income distributed by the King. Such a composition is largely based on that of the cardular registers, which have been used in the royal administration since Philippe Auguste; however, the Red Book innovates with the introduction of chronological recording, which makes it a more effective working tool, even though registration remains very incomplete, as it is left to the goodwill of the beneficiaries of the acts. The introduction of more systematic registration at the Royal Chancellery as early as 1307 makes the Red Book obsolete.