In accordance with Article 6 of Regulation (EC) No 396/2005, the applicant Tilco‐Alginure GmbH submitted a request to the competent national authority in Germany to modify the existing maximum residue levels (MRL) for the active substance potassium phosphonates in flowering brassica, Chinese cabbages, kales and spinaches. The data submitted in support of the request were found to be sufficient to derive MRL proposals for all the crops under assessment. Adequate analytical methods for enforcement are available to control residues of potassium phosphonates in the crops under assessment. Based on the risk assessment results, EFSA concluded that the long‐term intake of residues resulting from the use of potassium phosphonates according to the reported agricultural practices is unlikely to present a risk to consumer health. The consumer risk assessment shall be regarded as indicative and a more realistic intake assessment will be performed in the framework of the MRL review for potassium phosphonates. The reliable end points, appropriate for use in regulatory risk assessment are presented.