Interest taxation limited by treaty withholding rate; source state may tax but permanent establishment connection shifts taxation to business rules. Article 11 permits taxation of interest by the recipient's State while allowing the source State to tax interest paid to a resident beneficial owner subject to a treaty withholding limit. It broadly defines interest as income from debt-claims, excludes income covered by other Articles, and provides that where interest is effectively connected to a permanent establishment or fixed base the business taxation rules apply. Where special relationships cause interest to exceed arm's-length amounts, treaty benefits apply only to the arm's-length portion and the excess is taxable under domestic law.