I made this comment yesterday after the G7 tax deal was announced:
I have been asked what the biggest impediments to delivery of the new G7 tax deal are. Based on my experience at the OECD from 2013 - 2015 it’s easy to name them as PWC, Deloitte, EY and KPMG, who between them underpin the world’s tax havens.
— Richard Murphy (@RichardJMurphy) June 5, 2021
The comment was based on observation of what happened on country-by-country reporting, and my research.
The Big 4 all did all they could to oppose country-by-country at the OECD, although EY were the most aggressive, by some way.
As for research, work I did with Saila Stausholm at Copenhagen Business School showed just how fundamental the Big 4 are to offshore. Quite literally, they are the common thread without which the offshore world could not operate. Expect some opposition in that case. And most especially, expect them to open loopholes, because that is what they thrive on.