The giant charity established by tech titan Elon Musk could land him with a multi-million dollar fine because it has donated so little of its vast wealth.

The world's second-richest man has escaped billions in tax by gifting Tesla stock to the Musk Foundation which he set up in 2001.

But it gave away less than half of what it needed to for Musk to qualify for the tax break in 2022, and much of that went to employees, businesses and projects that he is personally associated with.

The billionaire SpaceX boss is one of just three people who run the foundation, one of whom reports devoting just six minutes a week to the task.

'The really striking thing about Musk is the disjuncture between his outsized public persona, and his very, very minimal philanthropic presence,' charity expert Benjamin Soskis told the New York Times.

Musk has created one of the world's largest charities with more than $7 billion in donations since 2020 alone.

But charities are required to give away at least five per cent of their assets each year to qualify for tax exemptions, but Musk's foundation barely managed two per cent in 2022, the last year for which records are available.