Multinationals are facing a potential seismic shift in how they are taxed around the world.

The OECD released a highly anticipated report May 31 outlining a blueprint for a global minimum tax and new rules for allocating a company’s profits among countries. If 129 jurisdictions agree to those principles by the end of 2020, they could then start a years-long process of adopting new rules through domestic legislation and changes to tax treaties.

The Organization for Economic Cooperation and Development’s...