The firm predicts the Chancellor will raise the rate of National Insurance Contributions above the Upper Earnings Limit (£34,840) from 1% to 2%. He might also introduce higher supplementary rates for top earners, such as a 3% levy on earnings above £100,000. Nigel May, Tax Principal at MacIntyre Hudson, says the chief attraction of this move is that it would only affect higher earners - those earning more than £670 a week - so would not ruffle the feathers of core Labour voters. Any move is likely to be deferred for a year, demonstrating the Chancellor has a strategy to tackle the budget deficit without further depressing the economy at this critical stage. The firm also predicts the Chancellor will raise the threshold for Stamp Duty from £125,000 to £150,000 and will introduce two new bands for Stamp Duty of 5% for property over £750,000 and 6% for property over £1 million. Over the past decade, Stamp Duty has proved to be Labour's golden goose, as rising property prices have pushed more transactions into the higher bands. Yet now both property prices and transactions are falling, threatening a serious loss of revenue. Faced with the Conservatives' popular plans to abolish Stamp Duty for first-time buyers of properties valued at up to £250,000, Darling could introduce a similar crowd-pleasing measure at the lower end, whilst still seeking to milk the cow at the top of the market.