Meghan and Harry have been living in her home city of Los Angeles, in Tyler Perry's $27m ($18m USD) mansion. Video / Inside Edition / Google
The Duke of Sussex faces a significant financial hit from the "zealous" US tax authorities, a royal financial expert has said, warning that the couple had not "thought through" the high cost of Californian life.
The Duke and Duchess spent more than US$14.6m ($22.3 million) on an impressive estate in Montecito, California, where they plan to live long-term and raise their son, Archie, in relative normality.
But once Prince Harry has spent 183 days in the US over a three-year period, he will be considered a resident for tax purposes and liable for tax.
David McClure, author of forthcoming book The Queen's True Worth, said: "California is a high tax state and he's likely to get a hit.
"I don't think Harry and Meghan have totally thought through the financial consequences of their exit from the royal family.
"The more their expenditure rises in California, the greater the pressure to generate their own income in more downmarket, commercial deals. That's always been the worry of the palace."
McClure said that the Duke would have to hand over much more detail about his personal finances and earnings than he would ever have had to do in the UK.
"The US taxman is much more zealous than his UK counterpart and for that reason, Harry will have to watch his step on the income he generates."
The Sussexes are estimated to have a joint worth of between £16m ($32m) and £20m ($40m). The combined outgoings of property tax, mortgage repayments, staff, security and the £18,000 ($36,000) a month they are repaying the UK taxpayer for the refurbishment of Frogmore House in Windsor, are vast, and have been estimated to reach up to £5m ($10m) annually.
The royal couple may soon hit another hurdle in their new life. Photo / Getty Images
Their Santa Barbara estate was purchased through a shell company listed at the Los Angeles address of Meghan's long term business manager, Andrew Meyer.
There are no names attached to the trust but the same address was used by the duchess when she set up her other companies, Frim Fram and MM Global, which McClure said could suggest they are worried about the tax implications of any association with Harry.
The type of visa he has travelled on will be key in determining his tax status.
It has been suggested he is unlikely to apply for a Green Card or citizenship, which would require him to renounce his titles and would make him liable for tax on worldwide income, including UK-held trusts.
Foreign citizens who marry an American and intend to reside in the US must obtain a US immigrant visa to become a lawful permanent resident.
It is possible that Harry used diplomatic status to enter the US but given that he is no longer working on behalf of the royal family, it is thought unlikely.
Another option could have been a 0-1 extraordinary ability visa, which he could have gained with the help of high profile backers and reliance on his unique status or the founding of an event such as the Invictus Games.
A spokesman for Harry declined to comment but insisted they would "follow the same legal requirements as everyone else".
