The final rate could go even higher than that, according to a Treasury release that said the 15% minimum is a "floor and that discussions should continue to be ambitious and push that rate higher."

U.S-based companies currently pay a 21% rate, a level that was slashed during the Trump administration. Previously, the top rate had been 35%.

Under a proposal from President Joe Biden, the tax rate would be lifted to 28%, part of a plan to raise levies on both companies and the highest earners.

But the White House wants to take its tax plans outside the border.

Treasury Secretary Janet Yellen has been touting the benefits of a global corporate minimum tax rate that she said would discourage companies from relocating domiciles to other countries to cut their tax burdens even though most of their operations are in the U.S.

Yellen's Treasury believes "that the international tax architecture must be stabilized, that the global playing field must be fair, and that we must create an environment in which countries work together to maintain our tax bases and ensure the global tax system is equitable and equipped to meet the needs of for the 21st century global economy," the department said in a news release.