PHILIP SMITH, journalist

October last year saw possibly the most significant move yet in the ongoing attempt to level the global playing field for taxation.

Amid much fanfare, the Organisation for Economic Cooperation and Development (OECD) announced a landmark deal setting a minimum 15 per cent corporate tax rate for the world's largest multinational companies together with the redistribution of tax rights over "super" profits.

The OECD estimates that the agreement will see countries collect around US$150 billion a year in new tax revenue and reallocate a further US$125 billion of profits from around 100 of the largest, most profitable companies. The two pillars of the agreement (ie the tax rights redistribution and the minimum tax rate) were subsequently endorsed by the G20 group of economies.

With the agreement due to be implemented by 2023, the hard work really begins now, in 2022. As OECD secretary general Mathias Cormann said, "Agreement without implementation is de facto no agreement at all, so countries must move as quickly as possible to bring both pillars into effect."

The two pillars

Pillar one of the agreement states that if a company has a global turnover of more than €20b and a profit margin of more than ten per cent, then 25 per cent of the profit in excess of ten per cent of revenue will be allocated to market jurisdictions using a revenue-based allocation key. A multilateral agreement will be developed and opened for signature in 2022 to implement the pillar, to be in force from 2023 onwards. This pillar will be reviewed seven years after implementation.

Pillar two sets a global minimum tax rate of at least 15 per cent. It will apply only to companies with a global turnover of more than €750 million. The minimum tax will work as a "top-up" tax that can be charged in the country where the multinational company is resident for tax purposes.

So, if a company pays two per cent corporate income tax in a foreign jurisdiction (such as a "source" country where they have operations or a tax haven that they are shifting profits through), then the tax-residency jurisdiction has the right to levy a 13 per cent tax on its profits. This gives additional taxation rights to the country where a company is headquartered, not where they do business.

Model rules

The first step towards implementation came just as 2021 was drawing to a close, with the release of a template for implementing the 15 per cent tax rate in the form of global rules to prevent the erosion of national tax bases. The rules are designed to:

• provide a co-ordinated system that defines which multinational companies fall within the scope of the minimum tax

• offer a mechanism for calculating the effective tax rate on a jurisdictional basis and for determining the amount of top-up tax payable

• impose the top-up tax on a member of a multinational in accordance with an agreed rule order.

The rules also address the treatment of acquisitions and disposals of group members, with specific rules addressing particular