While the deal has overcome some major impediments -- such as getting low-tax Ireland to sign on -- it faces several potential snags before it comes into force and proves effective, including the creation of a credible dispute resolution mechanism.
Signatory countries must also follow through by enacting domestic legislation to implement the new tax rules and by formally approving a multilateral convention, to be drafted by the OECD.
The U.S. and five European governments helped the agreement along with a side deal, announced Oct. 21. It allows the European countries to retain, for now, so-called digital services taxes on technology giants like Facebook Inc. and Amazon.com Inc., which U.S. officials said unfairly discriminated against American companies. That allows those nations to maintain revenues and keeps the pressure on Congress to approve the new rules over objections from top Republicans.