Many of the international financial centres around the world with low tax regimes are reacting with caution to the historic G7 tax deal which agreed a global corporation tax of at least 15% at the weekend.

Guernsey Government deputy Gavin St Pier said: "The devil, as it always is in tax, will be in the detail. It's aimed at this stage principally at large multinationals so it's difficult to know whether it's the end or just the beginning of the end for the zero-10 corporate regime we've had since 2008."

He argued it was also too early to try and detail the impact different parts of the finance sector and to "watch this space" with more international discussions ahead to fine tune the deal.

"As I've said many times before, Guernsey should have nothing to fear from a genuine level playing field. Let's hope that what emerges from the detail", he said.

The Isle of Man, which also has a Zero-10 policy to attract specific types of businesses to the crown dependency, notably international life companies, issued a statement from chief minister Howard Quayle.

He said: "As a forward thinking, small but agile, open economy the Isle of Man is well placed to adapt and respond to international standards as they evolve. Our record over the past two decades demonstrates this. The Isle of Man's long standing policy is to support international standards developed by organisations like the OECD that are adopted globally and provide for a level playing field."

Minster for the Treasury Alfred Cannan said: "Today's agreement at the G7 is an important step towards a potential global political agreement by the Inclusive Framework on Base Erosion and Profit Shifting.

"If global political agreement is reached significant further work will need to be undertaken at a global level in the coming months and years to bring these rules into operation. The Isle of Man will of course continue to engage closely with partners on the final detail of the framework.

"I recently announced a review of the island's economic strategy, which is being undertaken by KPMG on behalf of the Isle of Man Government, and taxation is a key part of this. We must seek to ensure that the Island continues to meet international standards while remaining competitive and an attractive place to live, work and do business."

The Jersey Evening Post reported that although it is expected it will take many years for the new minimum rate to be introduced, it will eventually bring an end to Jersey's zero-ten corporation tax regime.

Under the system, a large number of companies pay no tax, while certain sectors pay at a rate of 10% or 20%.

The zero-ten system was introduced in Jersey in 2009 after the EU Code of Conduct Group took the view that the Island's previous exempt-company-status regime was unfair.

The Irish Times reported that a 15% rate agreed by the OECD would mean Ireland would have to decide whether to increase the existing 12.5% rate to the new minimum.

It pointed out that US treasury secretary Janet Yellen highlighted mechanisms in the OECD agreement which would "essentially put pressure" on countries with lower tax levels to adopt the minimum rate.

These include the need for companies to make top up payments in their home country if a subsidiary had not already paid the minimum in another country, and a backstop to ensure a similar outcome via the use of tax credits if necessary.

Ireland has maintained that it is legitimate to retain the 12.5% to attract FDI here, but there is limited sympathy for the country's position.

And depending on the precise terms of the OECD deal and Biden's US tax reforms - if one is reached - there may not be much advantage to keeping the 12.5% rate.

UK chancellor Rishi Sunak hailed the "historic" decision by G7 countries to agree a global base rate of corporation tax and reforms to the tax system aimed at targeting online tech giants.

The decision to agree a minimum corporation tax would create a "more level playing field for UK firms and cracking down on tax avoidance".

While tax haven critic Richard Murphy, of Tax Research UK, who also visiting professor at Sheffield, City and Anglia Ruskin Universities, said: "You can be sure that all the UK tax havens plus Ireland, Cyprus, Luxembourg, Malta, and the Netherlands will all now be lobbying furiously to get this changed.

"They lose, and in some cases quite badly. I will not be crying for them: that was the aim. The USA, France, Germany, Italy and Spain win."

Murphy also asked where the UK stood on this issue: "Hard to tell, not least because of our intimate relationship with our tax havens and the fact that this deal so badly undermines the way they support the offering from the City of London. And as I note, how the deal works for smaller, let alone, developing countries is hard to say."

He added: "This is a big step forward in creating cross border taxing rights. But the devil is very much going to be in the detail and the need to get the interaction between accounting and tax right here is going to be very critical and very, very few people look at that. Without that issue being addressed this could be gamed into being almost irrelevant, and so there is a lot of robust negotiating to go."

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