The pre-budget report (PBR) runs to well over 200 pages, and the cynic in me says it's a deliberate ploy to hide bad news.  How's about this bit, buried on page 85: 

“the income tax personal allowance will be restricted for those with incomes over £100,000 – the two per cent of people with the highest incomes – from April 2010, when the economy is forecast to be growing. From that level of income, the personal allowance will be reduced at a rate of £1 of allowance lost for every £2 of income over that level until it is halved in value.”

Personal allowances are currently just over £6,000.  So if your income were to increase from £106,000 to £112,000 on 6 April 2010, what would that increase be worth to you?  Take off 1.5% for National Insurance = £90. Then take off 40% for tax on £6,000 = £2,400. And then take off 40% on your reduced personal allowance, which will have fallen by £3,000 = £1,200.  So out of a £6,000 pay rise, you’ll see just £2,310. Looks to me like an effective marginal tax rate of 61.5%.

And if you get a really good promotion, adding a further £40K to your income, the last £6,000 of your pay rise will be taxed at the same marginal rate.

In fact we’re going to see some quite extraordinary marginal tax rates going forward.  If you treat NI as nothing other than disguised tax, as income levels increase we’ll be looking at 0% below the NI threshold, 11.5% between the NI threshold and the personal allowance, 30.5% to the National Insurance upper rate band, then 41.5% up to £100K taxable, then 61.5% on the next £6K, back to 41.5% for the next £34K, back up to 61.5% for the next £6K, back to 41.5% for £4K, and then finally 46.5%.

Progressive taxation? Or just another example of ill-considered policy making on the hoof?