The invention relates to surfactant systems for liquid aqueous or aqueous-organic formulations containing a mixture comprised of one or several basic cosurfactants and one or several surfactants from the group of phosphoric acid esters. The surfactant systems enable the production of stable liquid formulations for active substances, whereby said formulations contain (a) one or several water soluble active substances (type (a)), (b) optionally one or several water-insoluble active substances (type (b)), optionally organic solvents and (d) the above-mentioned surfactant system and water. The formulations are either one-phase aqueous or aqueous-organic formulations of type (a) active substances, e.g. glufosinate-ammonium or glyphosate (salts) or microemulsions of type (a) and type (b) active substances, e.g. diphenyl ether herbicides.