A cartridge (11) for a correction ribbon (13) for typewriters comprises a container (12) for a supply reel (38) and a receiving reel (39). A tensioning device (46) comprises a toothed ring (47) on the supply reel (38) and a spring (48) which is pivoted in the container (12) and which has one end engaged with the toothed ring (47) to tension the ribbon (13). The container (12) can be removably fixed to the lower part of a cartridge for a typing ribbon which in turn can be fitted on a support of the machine. The support is movable from a viewing position to a typing position in which the typing ribbon is in front of the point of typing and to a correction position in which the correction ribbon (13) is in front of the point of typing. The receiving reel (39) of the cartridge (11), in use, is capable of co-operating with a feed mechanism which provides for forward feed movement of the ribbon (13) in each correction cycle. For that purpose the receiving reel (39) comprises a series of frontal teeth (66) provided in the lower part of its flange (63), the container (12) comprises an opening (74) and the feed mechanism comprises a ratchet co-operating with the frontal teeth (66) through the opening (74) for a forward feed cycle of the correction ribbon (13) when the support moves between the viewing position and the correction position.