Despite allegations of his "eviction" from the Royal Lodge, King Charles will back Prince Andrew.
The Duke's reduced income will include a guaranteed residence and private security costing roughly £3 million a year.
King Charles' proposals for a smaller monarchy will cut Andrew's £249,000 annual living payment.
The Duke's only other annual income is a small Navy pension.
In 2003, Andrew paid £1million for a 75-year lease on Royal Lodge, which he maintained.
The Grade II listed building is set in 98 acres of land and also boasts a swimming pool and a private chapel.
The Duke's ex-wife, Sarah Ferguson, also lives at the Royal Lodge with him, despite their divorce in 1996.
Andrew sold Sunninghill Park, a gift from the Queen, to a Kazakh billionaire for £15 million.
Andrew also received a large inheritance from the Queen and Prince Philip.