In this article, the author canvasses the legislation and common law jurisprudence that is relevant to the determination of the source of interest in Hong Kong. He argues that the source of interest is not susceptible to a single, over-arching test and that its ascertainment is by its very nature multifactorial. He contends that, in its Departmental Interpretation and Practice Note No. 13, the Hong Kong Inland Revenue over-relies on the judicial “provision of credit test” in its most simplistic form. In the absence of authoritative Hong Kong jurisprudence on the matter, the author advocates focussing the analytical inquiry not the locality of a debt with respect to which interest is payable, but the proximate source of the obligation to pay interest. Accordingly, other factors may be more important than the provision of credit test.