The present invention relates to a process for preparing sulfamoyl halides of primary or secondary amines, comprising the following steps: i) reacting a primary or secondary amine A1 with at least equimolar amounts of SO.sub.3 or an SO.sub.3 source in the presence of at least equimolar amounts of a tertiary amine A2, based in each case on the amine A1, and ii) reacting the reaction mixture obtained in step i) with at least the amount of a phosphorus halide required by the stoichiometry; The invention further relates to a process for preparing sulfonic diamides, comprising the preparation of sulfamoyl halides by means of carrying out steps i) and ii) and subsequently reacting the sulfamoyl halide obtained with ammonia. The invention further relates to the use of this process for preparing active herbicidal ingredients having a sulfuric diamide structure. The invention further relates to novel sulfamoyl chlorides.