This article gives methodological guidance on how best to compare the share of profits in value-added across countries using national accounts. Such comparisons are often based on accounts for institutional sectors such as non-financial corporations. It turns out that these are less internationally comparable than is usually assumed. The main issue is the allocation of certain types of self-employed workers to the corporations’ sector of some countries, most notably Germany and Italy. The consequence is that the measured gross operating surplus of corporations is overstated and has to be adjusted for international comparisons. If this is not feasible, it is preferable to rely on industry accounts, focus on a subset of industries and impute a labour compensation to self-employed workers for international comparisons. Profit shares in France, Germany, Italy and the United States are then much more similar than what the accounts for non-financial corporations suggest. The claim of a global increase in the profit share in the last decades is at best debatable for Germany and not backed with the evidence presented in this paper for France and Italy. It is only for the United States that we can confirm such an increase.