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 project, which started to address taxation of the digital economy, is now undertaking “a fundamental rethink of the basics of...