h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

a marginal rate of tax on income would be unfair if it exceeded 49%.
it is surely immoral if someone else takes the majority of the money you earn by the sweat of your labour. Isn't the worker worth his pay; he ought at least to retain the barest majority of his earnings.
the current marginal rate of tax on earnings for a person earning
£ 100,000 is in in excess of 70%, i.e. earn £ 10 keep only £ 3, earn £ 10,000, keep less than £ 3,000.
that's 11.34% paid by your employer in NI out of the £10,000 you earned him, 1% paid by you, 40% tax, and 20% tax clawed back via loss of your tax code. Next tax year, you and your employer each pay an extra 1% each, taking your loss to 3/4 of your extra earnings. If you've got any brains you'll vote the only way that works - with your feet.

One of the biggest factors in whether a tax is fair has nothing to do with how high the rate is; it's what you get for your money. I wouldn't worry too much about a 100% rate of tax if it meant I didn't have to pay for anything after that - but I'd object strongly to even a 1% rate of income tax if the only thing it went towards was a queen or president's private art collection.