The Singapore Standard Industrial Classification (SSIC) is the national standard for classifying economic activities undertaken by economic units and is used in censuses of population, household and establishment surveys and in administrative databases.

The SSIC adopts the basic framework and principles of the International Standard Industrial Classification of All Economic Activities (ISIC). It is reviewed and updated regularly to reflect significant changes in the structure of the Singapore economy and the emergence of new activities.

The Accounting and Corporate Regulatory Authority (ACRA) requires entities to declare their business activities during incorporation. Each entity must report at least one business activity (Principal Activity) but no more than two (Secondary Activity).

The SSIC follows a hierarchical principle of classification by Section, Division, Group, Class and Sub-class.