The transfer of nitrogen atoms is extremely valuable in the preparation of medicinal compounds. Here, a new system for NH transfer is developed to prepare sulfoximines, which are emerging as valuable motifs for drug discovery. This is achieved using readily available sources of nitrogen without the requirement for pre-activation or for metal catalysts in an operationally simple protocol. Mixing ammonium salts with diacetoxyiodobenzene in a choice of solvents directly converts sulfoxides to sulfoximines. The protocol is tolerant of many other functional groups and heterocycles that are important in drug compounds. This is the first example of the use of ammonia sources with diacetoxyiodobenzene providing a source of electrophilic nitrogen. Control and mechanistic studies suggest a short-lived electrophilic intermediate, likely to be PhINH or PhIN+.