Definitions of chargeable interest and credit institution determine scope and computation of interest tax liability under the Act. Section 2 defines key terms for the Interest tax Act: assessee (including persons under assessment or deemed in default), 'assessment' to include reassessment, and 'assessment year' as the annual period from April first. It defines chargeable interest as the total interest computed as provided, characterises the Board, and cross references undefined terms to the Income tax Act. The provision categorises credit institutions and several types of financial company, and defines 'interest' to include interest on loans and certain charges while excluding specified items.