There is a reason the OECD proposed two pillars for its gateway to a better tax future. A gateway requires both pillars, and neither can stand without the other. Pillar 2 is a fait accompli, but it needs countries to implement Pillar 1 as well because in the absence of a clear sourcing rule there is no limit to countries implementing the Qualified Domestic Minimum Top-Up Tax (QDMTT), which would turn off the other parts of Pillar 2 and potentially result in double taxation. Pillar 1 is not going forward in the absence of a Multilateral Tax Convention (MLC), but it can be implemented unilaterally, although that would require overriding existing tax treaties.