Permanent establishment rules determine when foreign enterprises have taxable presence via fixed places or dependent agents. Permanent establishment is a fixed place of business through which an enterprise's business is wholly or partly carried on, including specified examples and construction or supervisory projects exceeding nine months. Exclusions cover solely preparatory or auxiliary activities such as storage, display, delivery, stock maintenance for processing, purchasing, and information collection. Dependent agent rules treat persons who habitually conclude contracts, maintain stock to fill orders, or manufacture/process goods for the enterprise as creating a permanent establishment, while independent agents acting in the ordinary course are excluded unless devoted almost wholly to the enterprise or operating on non-arm's-length terms.