The EU–Fatty Alcohols decision of the Appellate Body addressed an important issue of the scope of permissible adjustments under Article 2.4 of the Agreement on Interpretation of Article VI of the GATT 1994, focusing on the ‘mark-up’ paid by an Indonesian exporter to a related company as a difference affecting price comparability between the export price and the normal value. The Appellate Body confirmed that the primary focus of the investigating authority's assessment is on whether the relationship between related companies can be demonstrated to be a factor that impacts the prices of the relevant transactions. This case raises the question of whether a harmonized approach to transfer pricing across different regulatory areas would be useful to bring greater consistency of treatment and certainty to international transactions.