RIMGROUP is a comprehensive cohort projection model of the Australian population which starts with population and labour force models, tracks the accumulation of superannuation in a specified set of account types, estimates non-superannuation savings, and calculates tax liabilities, social security payments including pensions and the generation of other retirement incomes.

These projections are done for each year of the projection period separately for each birthyear gender decile cohort. The model projections begin in July 2000.

RIMGROUP is a very large model incorporating 99,600 records, with many variables calculated for each record and with subgroups formed for those with different superannuation accounts and different retirement ages. Nonetheless, it is not an individually based microsimulation and there is some necessary ‘pooling’ of work experiences, account balances and income levels. For example, unemployment is viewed as a temporary phenomenon and superannuation accumulation is shared by those working and (temporarily) not working21. Similarly migrants are pooled with others in the model and may dilute the assets of the group they join.

Aggregate modelling based on RIMGROUP has been of considerable policy significance, see for example Gallagher (1995), Rothman (1997), Rothman (2007). It has been used in preparing both the First and Second Intergenerational reports (Intergenerational Report, 2007). More details of the RIMGROUP model and the current set of economic parameters used are in Attachment A.

21 But those permanently unable to work through disability are distinguished and treated separately.