The Duke of York's financial situation is mostly bankrolled by one person – his mother the Queen – but his income is "shrouded in a fog of secrecy", an investigator into royal finances has said.
With Andrew taking the unprecedented decision to step back from official royal duties, it will be up to the monarch to decide how much her son will continue to get from her private income – and this will never be disclosed.
The Queen receives £21.7 million a year from the Duchy of Lancaster, and uses an unknown amount of this private income to fund Andrew's royal duties and part of his private life.
His office at Buckingham Palace – where he has seven full-time staff plus, according to his website, two secondees from business and two interns from Huddersfield University, is paid for out of this Duchy money, as are any expenses incurred from official duties.
David McClure, a television producer and writer who examined the wealth of the royal family in his book Royal Legacy, told the PA news agency: "No-one knows for sure how much he gets.
"There is a mystery as to where Andrew's money comes from.
"We do know that he is funded by money from the Queen's Duchy of Lancaster estate but the precise details of that are shrouded in a fog of pea-souper proportions."
Mr McClure added: "There are also a lot of trusts knocking around. The Queen Mother left trusts. George VI left behind trusts, we think for his grandchildren, so more than likely there is trust money.
"Trusts are the traditional vehicle by which the royal family passes on their wealth."
Mr McClure added: "In theory, he probably needs less money.
"I think part of the problem is maybe the Queen's emotional attachment to her favourite son. She's both a head of state and also a mother, she must be torn in that respect. There are expenses to be paid."
The Duchy of Lancaster does not publish a breakdown of how the Queen spends her Duchy income, but Mr McClure called on the monarch to make her funding of the royals more transparent.
"Why can't the Queen through her annual statement give a breakdown of what she gives Andrew, Edward, Anne and Princess Alexandra?" he said.
The duke earned himself the nickname Air Miles Andy for his lavish use of helicopters and other aircraft at public expense.
Taxpayers footed the bill for his official royal travel via the Sovereign Grant, as they do with the rest of the royals.
As the duke steps away from public duty, his official royal travel should be non-existent.
But in 2011/2012, he clocked up a travel bill of more than £378,000 despite stepping down from his post as the UK's trade envoy in July 2011.
He continued to journey to countries in this role as he had previous commitments, carrying out five major tours promoting UK firms.
The total fee for journeys costing £10,000 or more in 2011/2012 came to £378,249.
His most expensive flights were £92,237 for travel to China, Hong Kong and Malaysia for a UK Trade and Industry (UKTI) tour in October 2011.
This included £19,987 for scheduled flights to and from the Far East and a further £72,250 on a private jet.
During that year, Andrew also spent £81,000 on a private jet to Saudi Arabia, a further £18,709 on scheduled flights to Singapore and £14,196 on tickets to Qatar and Abu Dhabi in November.
In 2016, he reportedly spent £5,000 of taxpayers' money flying in the royal helicopter to play golf at a club in Kent.
In 2004, two return trips to Scotland on an RAF jet for a golfing engagement at the Royal and Ancient Club in St Andrews cost taxpayers more than £10,800.
In 2009, the public paid £6,000 after he used a helicopter to fly 70 miles from his home to a bridge-opening ceremony in Sussex. A first class rail ticket would have cost £90.
The same year, the UKTI published figures that showed Andrew ran up hotel and transport bills in his role as trade envoy of more than £140,000 which were paid for by the government's international business development organisation.
In the most recent Buckingham Palace Sovereign Grant financial accounts of 2018-2019, records showed Andrew's scheduled flights to Bahrain on a trip for the Foreign Office in April 2018 cost £16,272, while a charter flight to Hungary for a Foreign Office trip plus scheduled flights for staff planning and advance trips cost £22,208.
The total for Andrew's travel was £38,480 – but the Buckingham Palace accounts only publish journeys costing £15,000 or more.
In total, the cost to the taxpayers in the last financial year for official travel for the Queen and the rest of the royal family was £4.6 million.
Mr McClure said: "In a sense there will be a saving to the public purse in so far as Andrew will not be taking public money for his travel expenses."
But a continued cost to the taxpayers will be Andrew's security bill.
The duke remains a senior member of the royal family, so will still have police protection officers.
But the amount the nation pays for guarding the royal family is never disclosed.
Mr McClure, however, said the figure for the royal family as a whole is likely to be in excess of £100 million a year.
"It's totally reasonable to assume that it's more than £100 million a year for royal security costs," he said.
"I still do not see why the Government can't give a ball-park figure... the figure would be embarrassing to be honest because it's so big."
Under the old Civil List arrangements, Andrew's salary for his official duties in the early 1990s was £249,000 from the taxpayer.
But in 1992 following an outcry over the monarchy's financial arrangements, it was decided the Queen would start to pay tax on her income and take over responsibility for meeting the working costs of most of her family.
Andrew also receives a Royal Navy pension, and it is likely he has his own portfolio of investments.
He is expected to retain his official residence at Buckingham Palace.
Andrew also has a private family home – Royal Lodge in Windsor Great Park – which used to be the Queen Mother's residence.
He sold his Sunninghill Park mansion – a wedding present from the Queen – for £3 million more than its £12 million asking price in 2007 to the son-in-law of the president of Kazakhstan.
The duke also bought a chalet in the Swiss resort of Verbier for a reported £13 million in 2014 with his ex-wife, Sarah, Duchess of York.
Andrew and Fergie
Andrew and Fergie
Sarah, Duchess of York and The Duke of York arriving during day four of Royal Ascot at Ascot Racecourse.
The Duke and Duchess of York leaving Portland Hospital in London with their first child four-day old Princess Beatrice.
File photo dated 23/07/1986 of Prince Andrew and his bride Sarah Ferguson waving to crowds as they leave Westminster Abbey, London after their wedding ceremony. When Princess Eugenie's parents married, Britain was in the grip of "Fergie Fever".
Duchess of York Sarah Ferguson (left) with the Duke of York in the parade ring during day four of Royal Ascot 2016, at Ascot Racecourse.
Sarah Ferguson, Jack Brooksbank, Prince Andrew, Duke of York and Princess Eugenie attend Day 4 of Royal Ascot on June 19, 2015.
Princess Beatrice of York (second left) Sarah Ferguson (centre), Princess Eugenie of York (second from right) and Prince Andrew, Duke of York (right) during day four of the 2015 Royal Ascot Meeting at Ascot Racecourse, Berkshire.
The Duchess of York, Sarah Ferguson and Prince Andrew at the finish of the 2010 London Marathon, on the Mall in central London.
The Duchess of York, Sarah Ferguson and Prince Andrew at the finish of the 2010 London Marathon, on the Mall in central London.
The Duke and Duchess of York arriving at All Saints Church in Odiham in Hampshire, for the Service of Thanksgiving and funeral of Major Ron Ferguson.
Princess Eugenie arrives with her parents, the Duke and Duchess of York, for her first day at St George's School, Windsor. Eugenie, 11, a granddaughter of Queen Elizabeth II, is a day pupil at the school, where she is expected to stay for two years. * before moving on to a senior school, possibly joining her sister, Princess Beatrice, 13, at St George's, Ascot. 06/11/02 The Duke told how Eugenie, now 12, is two inches taller after an operation to correct curvature of her spine while chatting to a 12-year-old hospital patient on a visit to the Uruguayan capital Montevideo.
The Duke of York with his daughters Princess Eugenie (left) and Princess Beatrice (right) during their ski-ing holiday in the Swiss Alps. The Duke was celebrating his 41st birthday on holiday with his ex-wife and children. * The birthday is a double celebration for the family, who toasted Princess Eugenie's success at passing a school entrance exam. Ten-year-old Eugenie's exam success means she will now enrol at a private school near Windsor Castle.
The Duke and Duchess of York, with their two daughters Beatrice (L) and Eugenie, arriving for the European Premiere of "102 Dalmations" at the Odeon cinema, in Leicester Square, London.
Princess Beatrice, daughter of the Duke and Duchess of York arrives for her first day at St George's School in Ascot, Berkshire, with her parents the Duke and Duchess of York.
The Duke and Duchess of York sit with their children Beatrice (Left) and Eugenie (Right) while they await the start of the tennis in the grounds of Buckingham Palace. The Duke of York organised the charity tennis event, to raise money for the NSPCC.
The Duke and Duchess of York arriving at the Serpentine Gallery 30th Anniversary Gala Dinner, in London. The Duchess is wearing a dress by Ben de Lisi.
The Duke of York celebrating his 40th birthday high above London in one of the gondolas of the Millennium Wheel with his ex-wife Sarah, Duchess of York, with whom he is still very close, and their daughters Princesses Beatrice and Eugenie. *The busy birthday is indicative of the Duke, who has said he is convinced that life really does begin at 40.
The Duke and Duchess of York arrive with their daughters, Princess Beatrice and Princess Eugenie (left), at the Warner Village, Leicester Square, for the Royal charity premiere of The Iron Giant. * An animated film, based on the short story by the late Poet Laureate Ted Hughes, which tells the story of a massive robot who falls to earth and is befriended by a lonely nine-year-old boy.
The Duke and Duchess of York arriving at Blakes Hotel in London, to attend a party in celebration of the Duchess's 40th birthday.
The Duke of York with his arm round the Duchess of York with Princess Eugenie, after the Duke joined the Duchess of York and their two children Princesses Eugenie and Beatrice in the Swiss ski resort of Verbier to celebrate his 39th birthday (19/2/99).
The Duke and Duchess of York (who are divorced) with their children Beatrice (r) and Eugenie, during a photocall in Verbier. The Duke, who celebrates his 39th birthday today, is on a sking holiday with his family.
Library file, dated 22/2/97.The Duke and Duchess of York, with their children Princess's Beatrice (right) and Eugenie, and the mother of the Duchess, Susan Barrantes, during a skiing trip in the Swiss resort of Verbier: It was announced today (Sunday) that Susan Barrantes has been killed in a car crash in Argentina. See PA story DEATH Barrantes. PHOTOGRAPH BY JOHN STILLWELL/PA.
The Duke and Duchess of York arriving at Wentworth Golf Club, Surrey, with their daughters Princesses Beatrice (right) and Eugenie, for the Duchess of York's fifth Charity Golf tournament in aid of the Motor Neurone Disease Association. y ROYAL Golf.
The Duke and Duchess of York with their daughters Princesses Beatrice (left) and Eugenie, at Wentworth Golf Club, Surrey, for the Duchess of York's fifth charity golf tournament in aid of the Motor Neurone Disease Association.
The Duke of York with Sarah, Duchess of York,and their daughters Princess Eugenie (left) and Beatrice, during the Pro-Celebrity Golf Tournament at Wentworth today (Monday) to celebrates the 5 anniversary of Children in Crisis. Photo by Andrew Stuart/PA
The Duke and Duchess of York and their children Beatrice and Eugenie arrive at the Pro-Celebrity Golf Tournament at Wentworth today (Monday) to celebrate the 5 anniversary of Children in Crisis. Photo by Andrew Stuart/PA
The Duchess of York with former husband the Duke of York, during a photocall with their daughters Princesses Beatrice (right), nine, and seven-year-old Eugenie in Verbier, Switzerland today (Thursday). PA PIC NEIL MUNNS. See PA Story ROYAL Duchess. 07/03/98: The Princesses could be stripped of their HRH titles in a round of reforms to further modernise the monarchy, announced today (Saturday). The proposals include restricting the style His or Her Royal Highness to senior royals; confirming that bowing and curtseying to royals is not compulsory; and finally closing the door on palace grace-and-favour accommodation. See PA Story ROYAL Reform.
The Duke and Duchess of York and their daughters Princess Beatrice (2nd left) and Eugene arrive at Westminster Abbey for the funeral of Diana, Princess of Wales today (Sat).
The Duke and Duchess of York were reunited briefly today (Monday) at a charity golf match in aid of motor neurone disease. They posed together for photographers with their daughters the Princesses Beatrice (left) and Eugenie at Wentworth Golf Course in Surrey. Photo by John Stillwell. See PA Story ROYAL York.
The Duke and Duchess of York with their daughter's Beatrice (right) and Eugenie on the Swiss ski slopes above, the ski resort of Verbier. Photo by John Stillwell/PA.
The Duke and Duchess of York appearing together for the first time sinc etheir decree absolute was finalised. they and their daughters were at wentworth golf club for a charity event for motor neuron disease association.
The Duke of York gives his wife a kiss at Wentworth golf club where he took part in a pro-am golf tournament in aid of motor neuron disease association- of which the Duchess of York is president.
The Duke and Duchess of York and their youngest daughter Princess Eugenie enjoy the events of sports day at Upton House School, Windsor which is attended by their other daughter Princess Beatrice.
The Duke and Duchess of York attending the Royal Windsor Horse Show with their daughters Princess Beatrice (left) and Eugenie. 16/04/1996 : The couple announced that their marriage is to be formally ended in divorce, following more than two years separation.
The Duke and Duchess of York enjoy the events of sports day at Upton House School, Windsor which is attended by their daughter Princess Beatrice.
The Duke and Duchess of York board HMS Cambeltown at Portsmouth Harbour prior to a days sailing in the channel with the Queen and the Duke of Edinburgh.
The Duke and Duchess of York onboard HMS Cambeltown in Portsmouth Harbour prior to a days sailing in the channel with the Queen and the Duke of Edinburgh.
The Duke and Duchess of York at Heathrow Airport with their two daughters, Beatrice (in the Duchess's arms) and Eugenie (in the cot). The Duchess flew out to see her stepfather in Argentina, who is diagnosed as having lymphatic cancer.
The Duke and Duchess of York pause outside the Portland Hospital in London with the duchess holding their new daughter Princess Eugenie Vistoria Helena.
The Duke and Duchess of York with their daughter Princess Beatrice at the Royal Windsor Horse Show.
The Duke and Duchess of York during a tour of USS Nimitz, on their 'Buy British' tour of California.
The Duke and Duchess of York dressed in period costumes at the replica Klondike village in Port Edmonton, Alberta during their first official tour together in Canada before setting off on a two-week canoeing holiday in the Wild North West Territories
The Duke and Duchess of York applaud competitors taking part in games for the physically disabled at the Ontario Games in Toronto during their offical 12-day visit to Canada.
The newly created Duke of York and Duchess of York wave from the balcony of Buckingham Palace after their marriage at Westminster Abbey.
The newly-wed Duke and Duchess of York wave as they board the jet at Heathrow Airport, London, carrying them to the Azores for their honeymoon.