Each membership category, with the exception of Associate and Retired, allows the member to use the IoD postnominal that reflects their membership category.
Associate – No postnominal applies
Member – MInstD
Chartered Member – CMInstD
Chartered Fellow – CFInstD
Distinguished Fellow – DistFInstD
Retired Fellow – FInstD (Retd)
Retired – MInstD until 2020, then no postnominal applies