The Two-Pillar Solution acknowledges the importance of the STTR in achieving a consensus on Pillar II for developing countries, but so far has only identified interest, royalties and a “defined set of other payments” as being subject to the rule, has set the minimum rate for the STTR at a range from 7.5% to 9% and has relegated implementation to a bilateral negotiation upon request. This panel will explore the practical tension inherent in the Pillar II proposals in addressing the concerns of developed and developing countries with a particular emphasis on the challenges faced by developing countries in protecting their tax base and competing for revenue.