Of all the embarrassing stories that have come out about Rupert Murdoch over the years, it is hard to go past today’s revelations in The AFR that he short-changed his own mother and then left her with a huge tax bill.

For those observers who have long questioned why News Corp has been so tight-fisted with its dividend payments, the answer might have been unearthed by Neil Chenoweth, The AFR reporter who literally wrote the book on Rupert’s financial wheeling and dealing.

Dame Elisabeth Murdoch turns 99 on 2 February next year. She still lives on Cruden Farm, the unencumbered property on Melbourne’s outskirts which Sir Keith Murdoch left her when he died in October 1952.

Sir Keith’s will specified that his wife received 10% of the income from four family trusts that he left. The assets would pass to Rupert after Dame Elisabeth’s death.

Lo and behold, Rupert caused the entire amount to be invested in News Corp shares which pay pathetic dividends. Two different QCs concluded that this diddled Dame Elisabeth at the time he was negotiating the $600 million buyout of his three sisters after News Corp almost went to the wall in the early 1990s.

Rupert signed a deed in 1994 to say he was fixing things up. His mum got an $85 million payment by way of a capital reduction, but she then passed $55 million of this straight back to Rupert and now she’s copped an estimated $100 million tax bill as she approaches a century of a different kind.

The AAT tax judgment is an absolute belter, although the names were only revealed in recent days when the trustees appealed against the huge bill in the Federal Court.

For such a dedicated tax planner, it is ironic that Rupert’s mum has copped this huge bill when the family’s entire stake was tax free. If Rupert had simply sold some News Corp shares and paid out the cash to his mum, none of this would be happening because the stake pre-dates capital gains tax which came in 22 years ago.

This whole saga is a cracking story and we all look forward to it being properly covered by The Australian, The Wall Street Journal, The Times and the various other quality newspapers in the News Corp stable.

Indeed, how about a tell-all interview with Rupert for the opening day of the new Fox Business Channel on October 15.