According to reports, Prince Harry risks a “monumental tax bill” unless he “takes a break” from his £11 million Californian mansion.

After leaving a leased property in Vancouver, Canada, Harry, his wife Meghan, and their baby Archie relocated to Los Angeles in early May.

The family was initially believed to be residing in a Beverly Hills property owned by Tyler Perry.

As of October 4, the Prince has been in the United States for 151 days, and if he reaches 183 days, he will be required to pay taxes in the country.

David Holtz, the chief tax attorney in Los Angeles said, “You can safely assume that someone at the Internal Revenue Service [IRS] is looking very closely at him. This is a big deal.”

According to the Mail on Sunday, Harry now faces paying both US federal and Californian state taxes under the Internal Revenue Service’s ‘substantial presence test.’

“Harry’s bill could be monumental,” another tax expert told the Mail on Sunday, “and could open up a can of worms for the Royal Family because the IRS will want to know all of his sources of income.”

The income will be determined using not just the couple’s Netflix arrangement, but also any money he got from Prince Charles and any trust funds, savings accounts, or other assets he holds in the UK, according to the expert. That implies the Royal accounts will be scrutinized. The taxman in the United States is significantly more ardent than his equivalent in the United Kingdom.

“Meghan is a US taxpayer, and her situation hasn’t changed,” said another accountant, “but Harry will have to tell the IRS about every penny he has received.”

“That includes paying gift tax on any monetary gifts he received from Prince Charles and he will have to show any other source of income including trust funds set up after the death of Princess Diana.”

The Duke and Duchess of Sussex, who now reside in Montecito, California, are reported to be worth £20 million.

If Harry entered the US on a diplomatic visa, he would be free from paying taxes; however, if he arrived on a 0-1 visa for persons with “extraordinary abilities,” he will be subject to the same taxes as everyone else.

Mr Holtz said: “If Harry’s been in the US for 183 days straight then he’s done.

“But it is safe to assume they have had lawyers and tax experts grinding away on this issue for months.”

It comes as the former Army chief makes an unprecedented public call for Prince Harry to return to the UK.

General Sir Richard Dannatt believes veterans will suffer as a result of Harry’s choice to leave the royal family and relocate to America with actress wife Meghan Markle.

He believes it is a pity that the prince is no longer associated with armed forces organisations that assist injured or disturbed veterans, such as Help For Heroes and Walking with the Wounded.

General Dannatt said: “Harry and Meghan are very much involved in other things and that’s their life choice and I don’t criticise them for that.