Issues with an international context are commonplace in German law firms. However, the field of international tax law is often underestimated, leading to suboptimal tax decisions in consultations. This work explains the fundamentals and provides numerous tips for advisory services. It specifically addresses the following areas: - Tax peculiarities in cross-border delivery and payment transactions - International tax law and procedural issues - Inbound and outbound - Case structures - Double taxation agreements - Avoidance of double taxation - Taxes in foreign relations (trade, inheritance, sales, and consumption taxes). Thus, this work serves as a compact guide for consulting in international tax law.