In accordance with Article 6 of Regulation (EC) No 396/2005, the applicants De Sangosse SAS and Tilco-Alginure submitted two requests, respectively, to the competent national authorities in France and Germany to modify the existing maximum residue levels (MRLs) for the active substance potassium phosphonates in various plant commodities. The data submitted in support of the requests were found to be sufficient to derive MRL proposals for the commodities under assessment. For the derived MRL on baby leaf crops, further risk manager consideration is required to decide between two MRL options. Adequate analytical methods for enforcement are available to control the residues of potassium phosphonates in accordance with the residue definition 'phosphonic acid and its salts expressed as phosphonic acid' in the commodities under consideration. Based on the risk assessment results and assuming that the existing MRLs will be amended as proposed by EFSA in previous outputs, EFSA concluded that the long-term intake of residues resulting from the existing uses of fosetyl and phosphonates (previously assessed in a joint MRL review) and new proposed uses of potassium phosphonates is unlikely to present a risk to consumer health. Considering the toxicological profile of the active substance, a short-term dietary risk assessment was not required. The risk assessment shall be regarded as indicative because some MRL proposals derived by EFSA in the framework of the MRL review according to Articles 12 and 43 of Regulation (EC) No 396/2005 require further consideration by risk managers.