Country Representative Members (CRMs): Membership fees are calculated on an individual basis, using the society's score on the United Nations Scale of Assessment which covers every recognised country.
International Members at Large (IMALs): The fee for an International Member at Large is the CRM fee level that applies to the country of the headquarters of the IMAL or its legal seat if no headquarters exists.
National Members at Large (NMALs): The fee for a National Member at Large is a proportion of the fee for the CRM of that country and depends on the number of NMALs there are for the country at the beginning of the year in accordance with the following table
|Number of NMALs||Proportion of the CRM rate payable by each NMAL|
|3 or more||0.2|