Permanent establishment defined as fixed place of business; agency and excluded preparatory activities determine tax presence and obligations. The permanent establishment concept applies where an enterprise carries on business through a fixed place of business, with specified examples and a temporal threshold for construction sites. Activities that are purely preparatory or auxiliary are excluded. A dependent agent who habitually concludes contracts or maintains stocks for delivery can create PE status, whereas independent agents acting in the ordinary course of business do not. Insurance enterprises collecting premiums or insuring risks through non-independent agents are deemed to have a PE. Corporate control alone does not constitute a PE.