King Charles has become Britain’s first monarch in modern times to reveal how much tax he pays on his private income: £24.6m over the last two years.It’s a move celebrated by some as heralding an era of greater transparency from the monarchy. But just how open has it been? Why has the king published his tax bill?Buckingham Palace said that it was the “express wish” of the monarch to publish this piece of information. His aides say the decision is part of a wider drive to be more open with the public.Sceptics, however, point out that the royals have endured a run of bad publicity over Andrew Mountbatten-Windsor, prompting MPs to demand more information about their finances. The king will also be aware of the need to assuage public opinion at a time when more Britons appear to be questioning the existence of the monarchy.How significant is the publication?The royal finances have been described as shrouded in fog, and Thursday’s tax declaration does little to clear it. British monarchs are not liable for tax, but the king and his mother before him started paying it voluntarily in 1993. The amount payable has been declared for the first time this year, but very little else has been revealed.All we have is a line in the royal household’s report, which states: “His majesty’s tax payable for 2024-25 was £12.9m (2023-24: £11.7m). The total amount of tax payable by his majesty since accession to the throne is more than £30m.”The income on which the king owes tax has not been declared. We know he received £25.2m from the Duchy of Lancaster in 2025-2026 (up from £24.4m the year before), but earnings from his private estate, which includes financial investments and property, remain under wraps.Another unanswered question is how much the king deducted from his Duchy income for official expenses. Any money spent in the course of his duties is tax exempt. It could amount to millions, but the figure hasn’t been declared.How wealthy is the monarch?The publication of the king’s tax bill will do little to illuminate the big question of how wealthy he is.The extent of his personal fortune is by and large concealed from public view. The Windsors’ personal finances have habitually been enveloped in entrenched secrecy. The Guardian, however, conducted a comprehensive audit of the king’s assets – from country piles and diamond-encrusted jewels, to paintings by Claude Monet and Salvador Dalí, Rolls-Royces, racehorses and rare stamps – in 2023.It estimated his personal wealth at £1.8bn. Buckingham Palace said the figure was a “highly creative mix of speculation, assumption and inaccuracy”, but that it had a policy of refusing to comment on the royal family’s personal finances.Are there are other things the king could do to increase transparency about the royals’ finances ? Yes: