The Organisation for Economic Co-operation and Development (OECD) has promoted the adoption of internationally standardized transfer pricing rules to curb profit shifting for tax avoidance by multinational firms. In a 2023 study, Bustos and colleagues analyzed a major reform in Chile based on these OECD standards and found that it led to a surge in tax advisory services. This paper investigates the external validity of this finding. Combining employment history data with information on countries’ strictness of transfer pricing regulations over time, we analyze the effect for four countries: Chile, Colombia, Spain, and Uruguay. Event-study difference-in-differences analysis shows that reforms led to substantial increase in transfer pricing consultants in most cases. The effect is larger when the reform is stronger and when a country has a lower level of pretreatment transfer pricing strictness or of transfer pricing consultants.