The assumption of a full utilisation of
resources can be true for physical resources
like materials, but is highly unlikely the case
for intangible resources such as IT services.
TDABC and RCA models acknowledge the
fact that idle resources may exist in an
organisation’s normal course of business as
committed resources may not be fully utilised.
Therefore, the two models attach resource
costs to individual units of a resource.
Resource costs are allocated to a cost pool only
when resources are actually consumed by that
cost pool. Resources that are not utilised in
operations (idle resources) are recognised in
the two models and costs associated with idle
resources are not allocated to any cost pool.