Global leaders of the world’s 20 largest economies agreed on Saturday to move ahead with the proposal to establish an international corporate tax of at least 15% to stop multinational businesses from taking advantage of some countries’ low tax rates.

This G20 plan marks the most significant overhaul of the international tax system in decades and has the potential to reshape the global economy, including where companies choose to operate and who gets to tax them. 

The details of the plan remain unclear and finance chiefs have until October to finalize the proposal before they reconvene at a summit in Rome. 

“After many years of discussions and building on the progress made last year, we have achieved a historic agreement on a more stable and fairer international tax architecture,” the finance ministers said in a joint statement at the conclusion of the meetings.

This landmark deal could also turn the global economy upside down. 

Experts told CNBC that the cross-border tax loopholes are ultimately likely to fail to remove the incentive for some of the world’s largest companies to shift their profits abroad. Some even describe the proposed reform as “shockingly” unfair for low-income countries. 

So far, 132 countries have signed up to the G20’s “Inclusive Framework,” but several low-tax countries are not as enthusiastic about the terms of the deal.

This deal is expected to impact many companies, including Amazon, Google and Nike.

“It really will be a dramatic shift in terms of the business model of the corporate tax havens. It won’t be the absolute end but the more tightly the deal is defined, the more comprehensively that business model will be finished,” Alex Cobham, chief executive of the Tax Justice Network, told CNBC