Permanent establishment rules define when a foreign enterprise constitutes a taxable presence and when exclusions apply. A permanent establishment is a fixed place of business through which an enterprise conducts business, including management offices, branches, factories, workshops, extraction sites, warehouses providing storage for others, agricultural sites, sales outlets, and long-term installations or construction projects exceeding specified durations, and service activities performed through personnel when they exceed specified aggregation periods or are for related enterprises. Exclusions cover preparatory or auxiliary activities, mere storage or display, stock held for processing, purchasing or information collection. Agency rules deem an enterprise to have a permanent establishment where an agent habitually concludes contracts, maintains delivery stock with contributory activities, or secures orders, while independent agents acting in the ordinary course generally do not.