The structure of the ICATUS categorizes SNA-work activities engaged in by individuals into two major groups in relation to the institutional unit that produces the output— activities performed by individuals as household members that input into household production and activities performed by individuals that input into production of units belonging to sectors other than the household sector. For this purpose, institutional units are defined and classified following the 1993 SNA, as follows:

An institutional unit is “an economic entity that is capable, in its own right, of owning assets, incurring liabilities and engaging in economic activities and in transactions with other entities.” There are two main types of institutional units, namely: (a) persons or group of persons in the form of households and (2) legal or social entities whose existence is recognized by law or society independently of the persons, or other identities, that may own or control them.” These units are classified into:
(1) Corporations and quasi-corporations including cooperatives and limited liability partnerships
(2) Government units, national or local
(3) Households
(4) Non-profit institutions (NPIs)

Similar institutional units are grouped into five mutually exclusive institutional sectors:
(1) Non-financial corporations sector, including NPIs
(2) Financial corporations sector, including NPIs
(3) General government sector, including NPIs
(4) Non-profit institutions serving households (NPISH) sector
(5) Household sector