GST on penal interest: seller charged penal interest is includible in supply value, lender interest may be exempt. Additional or penal interest on delayed EMI payments is taxable when charged by the seller because it must be included in the value of the supply of goods; penal interest charged by a separate lender on a loan qualifies as exempt interest under the exemption for extending loans or advances, provided it meets the statutory definition of 'interest'. Penal interest meeting that definition is not a separate taxable service under the provision covering tolerance or abstention, while service fees or other non interest charges by a financier are taxable.