US treasury secretary Janet Yellen on Sunday said that a newly endorsed mechanism to allow more countries to tax large, highly profitable multinational companies may not be ready for consideration by lawmakers until spring 2022.

Yellen told a news conference after a G20 finance leaders meeting in Venice, Italy, that the OECD reallocation of taxing rights was on a “slightly slower track” than a global corporate tax of at least 15 per cent as part of a tax deal among 132 countries.

G20 finance ministers and central bank governors endorsed the deal over the weekend, but questions remain over the ability of US President Joe Biden’s administration to persuade a deeply divided Congress to ratify the changes.

Yellen’s comments suggest a two-step process for implementing the OECD tax deal, with the global minimum tax moving first.

She said she hoped to include provisions to implement the so-called “Pillar 2” minimum tax into a budget “reconciliation” bill this year that Congress could approve with a simple majority, potentially without Republican support.

The “Pillar 1” portion of the agreement would end unilateral taxes on digital services in exchange for a new mechanism that would allow large profitable companies to be taxed in part by countries where they sell products and services, rather than just those hosting their headquarters or intellectual property.

“Pillar 1 will be on a slightly slower track. We’ll work with Congress,” Yellen said, when asked whether a two-thirds majority would be needed in the US Senate, which is normally the requirement for international treaties.

“It may be in ready in the spring of 2022 and we’ll try to determine at that point what’s necessary for its implementation,” Yellen said.