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As the United Kingdom prepares for the Coronation of its first king in 86 years, a very specific cause overlooked by its latest Queen has once again surfaced.

It has to do with the UK monarch's role in overseeing a sprawling network of tax shelters that conceal billions of dollars of global wealth a year.

In a letter to King Charles III, dashed off in this week of his Coronation, the UK's Tax Justice Network, a group of academics, activists and researchers, asked the King to embrace past assurances of building a transparent, modern-day monarchy by breaking up his web of satellite tax havens, which it estimates causes around £152 billion of taxes to go unpaid globally every year.

Tax avoidance may seem like an abstract issue to some, but it is due to the tax shelters used by the world's wealthiest individuals and monster businesses that nations are starved of the funds they need to support their citizens. As the U.S. and other countries continue to witness battles over taxation, government debt and the rising global wealth gap, the role of tax shelters will increasingly take center stage.

Recent research shows that if the losses caused by the UK's Crown dependencies and overseas territories were reversed, 6.4 million people would have greater access to drinking water, 12.6 million would have access to sanitation and 1.2 million children would be able to attend school longer.  

Because these tax shelters operate under the King and are part of one, undivided realm of the UK monarchy, it is within the King's purview to rein them in – although, in the past, the Queen resisted doing so.

In its letter, the Tax Justice Network reminds the King he made a statement last year touching on the need to "find new ways to acknowledge our past."

The group asked him to reflect on "the enduring impacts of slavery and other aspects of colonial violence and extraction" and how "many of today's British satellite tax havens are an unresolved legacy from that time, having been facilitated to develop as financial and secrecy centers." It added that "these tax havens continue to disadvantage their own inhabitants, as well as some of the poorest people globally – and, of course, the people of the UK."

More concretely, Tax Justice Network expressed concern that the UK, Crown dependencies and British overseas territories "are collectively responsible for facilitating nearly 40 percent of the tax revenue losses that countries around the world suffer annually to profit-shifting by multinational corporations and to offshore tax evasion by primarily wealthy and powerful individuals."

The group noted, "This makes the UK and its network of satellite tax havens the world's biggest enabler of global tax abuse." The letter was also sent to the UK's prime minister.

Curbing global tax abuse and illicit financial flows are among the U.N.'s Sustainable Development Goals for 2030, as there is "growing consensus that global tax abuse robs states of the resources to fulfill their obligation as duty-bearers of human rights," the letter said.

The letter exhorted the King to revamp his tax shelters, stating, "We believe Your Majesty can help by pointing the way to end one of the world's most enduring injustices."

That said, if the King were to do so, the Royal Family would also have to stop using tax shelters themselves.