Variations in the wording of similar provisions of existing bilateral treaties can be addressed through superseding language in a multilateral instrument. Introducing multilaterally agreed changes through a multilateral instrument may raise technical challenges due to variations in the wording of existing bilateral tax treaties. Whether this is a real issue will depend largely on the extent to which each treaty based output of the BEPS Project is a stand-alone measure which easily complements existing treaties, or relies heavily on existing concepts that are already defined in model tax conventions. If a given output of the BEPS Project relies on an existing concept, and those concepts do not appear, or have an alternative meaning, in some bilateral
treaties, a multilateral instrument will be unable to assume uniform
usage of the Model Tax Convention concept.