defined by longitudinally and transversely extending non conducting portions in which the metal coating has been removed from the card that pattern can be read to identify the credit card the area 5 represents an initial credit and can be marked beginning at 6 by a marking appliance which will be described more fully hereinafter for making successive deductions from said credit the remaining credit can be read by means of scale imprints 7 and 8 as ist apparent from fig2 the scales 7 and 8 provided with printed numerals 9 permit the user of the credit card to read from the area 5 how much of the initial credit has been deducted for this purpose a portion of the metal coating on the area 5 is burnt off in each deducting step the total area which has been burnt off is designated 10 when the numerals 9 and other inscriptions are printed on the credit card bars 11 12 and 13 are also printed on the card these bars cover the transversely extending non conducting portions which define the isolated portions 3 in the embodiment shown in fig2 the credit card has only a credit capacity of e g 20 value units fig2 shows a double credit card having a double credit capacity if this card is provided with a.