The fact that the arm’s length standard is anchored in the separate-entity principle yields a transfer pricing analysis that almost neglects the integrated economic reality of the group of companies. While tax law builds up this fiction of related companies acting as if they were stand-alone companies, corporate law has been more responsive to the economic reality of the group. Such integrated economic reality in groups of companies requires a specific response of tax law rather than simply ignoring the power dynamics under the separate legal entity principle. The need to reframe the arm’s length standard to match the group dynamics has become urgent under the new profit allocation rules derived from the OECD Unified Approach, which allocates the deemed residual profit while taking into account the group as a whole. In light of the above, this article challenges the current arm’s length standard, which completely sidesteps the power dynamics in the transfer pricing analysis for tax purposes. Reintroducing such power dynamics in the analysis leads to the notion of “group interest” coined in the field of business law. Group interest, premised on horizontal fairness and legal certainty, serves the author to reconsider the statement that related parties are equal to stand-alone companies. Enforcing group interest within the arm’s length standard leads to the introduction of rebuttable presumptions, which are applied to three specific areas of transfer pricing: profit allocation to dependent agent enterprises, the commercial rationality test and group synergies. Group interest does not aim to replace the arm’s length standard, but to readjust it to group power dynamics and, thus, ensure the endurance of the arm’s length standard in the context of the digitalized economy.