The invention provides anticorrosive flame retardant formulations for thermoplastic polymers, comprising from 20 to 97.9% by weight of a (di)phosphinic acid salt of formula (I) and/or (II) wherein R1, R2 are the same or different and denote H or C1-C6-alkyl, linear or branched, and/oFr aryl; R3 denotes C1-C10-alkylene, linear or branched, C6-C10-arylene, C6-C10-alkylarylene or C7-C20-arylalkylene; M denotes Mg, Ca, Al, Sb, Sn, Ge, Ti, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, K and/or a protonated nitrogen base; m denotes from 1 to 4; n denotes from 1 to 4; x denotes from 1 to 4, and as component B from 2 to 50% by weight of a phosphazene of the general formula (III) or (IV) wherein R4 and R4′ are the same or different and represent C1-C20-alkyl, C6-C30-aryl, C6-C30-arylalkyl or C6-C30-alkyl substituted aryl, and X represents a group —N═P(OPh)3 or —N═P(O)OPh and Y represents the group —P(OPh)4 or —P(O)(OPh)2; as component C from 0.1 to 30% by weight of an inorganic tin compound, and as component D from 0 to 50% by weight of a nitrogen-containing flame retardant.