The deal was notable for the inclusion of countries that had been skeptical, including China, Russia and India, tax experts said.

Still, a great deal of work remains before a global minimum tax will become a reality. Participating countries must hammer out agreement on numerous details, bringing into alignment national tax systems that differ in important respects.

“It is a very, very broad-brush document. Now we have to work to get the details,” said Catherine Schultz, vice president for tax and fiscal policy at the Business Roundtable.

Every country will not be required to adopt the same 15% corporate tax rate. But if a country maintains a lower rate, the United States would be able to impose a compensatory levy on companies headquartered there, achieving the same objective.

The agreement on taxing the profits of Internet companies even where they lack a traditional brick-and-mortar presence seems especially complex. The levy applies to multinational corporations with annual sales of more than 20 billion euros, or roughly $24 billion, and before-tax profit margins above 10%.

“It requires an unprecedented degree of cooperation and coordination among countries, not just in the design of rules but in their application, permanently,” said Barbara Angus, global tax policy leader for Ernst & Young. “There’s a lot of work to be done.”

A handful of countries did not sign on to the blueprint, including Ireland, a nation that has used its 12.5% corporate tax rate to attract U.S. technology and pharmaceutical companies over the past half-century. Likewise, Hungary and Estonia abstained, further complicating prospects for full European Union endorsement.

Each of the 130 nations, including the United States, also must convert its endorsement of Thursday’s five-page plan into the nitty-gritty detail of legislation that will rewrite individual tax codes.

The OECD statement said the two-pronged accord would reallocate the right to tax $100 billion in digital companies’ profits from their home nations to countries where they earn money even if they lack a physical presence there. The deal also sets a minimum corporate profits tax of “at least 15 percent,” which is expected to raise $150 billion annually, according to the OECD.

The tax overhaul comes after several decades that saw policymakers lighten the tax burden on big business.

Since 1980, the global average corporate tax rate, weighted by the size of each economy, has dropped from more than 46% to 26%, according to the nonprofit Tax Foundation. While good news for corporations and investors, the decline has made it harder for governments to fund popular benefits and other programs.

President Donald Trump complained that other countries were using low tax rates to steal U.S. jobs, and Republicans in 2017 passed legislation reducing the corporate tax rate from 35% to 21%.

Biden has proposed raising the rate to 28% to free individual taxpayers from more of the cost of expanding government programs. He also has proposed a 15% minimum corporate tax rate to prevent companies from using exemptions and deductions to effectively eliminate their tax liabilities.

In the United States, annual revenue from corporate taxes relative to the size of the economy is now less than a quarter as large as in 1967, according to the Congressional Budget Office.

The burden-sharing issue has grown only more acute as the coronavirus swept the globe. Governments worldwide spent a collective $16 trillion over the past year to fight the pandemic’s health and economic ills, according to the International Monetary Fund.

“This historic package will ensure that large multinational companies pay their fair share of tax everywhere,” OECD Secretary General Mathias Cormann said. “This package does not eliminate tax competition, as it should not, but it does set multilaterally agreed limitations on it. It also accommodates the various interests across the negotiating table, including those of small economies and developing jurisdictions. It is in everyone’s interest that we reach a final agreement among all Inclusive Framework Members as scheduled later this year.”

The global minimum tax is an essential element of the president’s plan to raise the corporate tax rate at home, by minimizing the incentive to move offshore to escape tax collectors. But early reaction from some prominent Republicans to the OECD statement was sharply negative.

“This is a dangerous economic surrender that sends U.S. jobs overseas, undermines our economy and strips away our U.S. tax base,” said Rep. Kevin Brady of Texas, the senior Republican on the tax-writing House Ways and Means Committee.

Implementing the sweeping proposal would present its own challenges. Administering the new tax on digital companies would require “coordination between the IRS and other tax authorities on a day-to-day basis that we’ve never seen before,” said Angus, a former chief tax counsel for the Ways and Means panel.

Negotiators aim to reach a final deal by the end of October, when the Group of 20 leaders are scheduled to meet in Rome, with implementation to start in 2023.