The rich face closer scrutiny of their tax affairs after the launch of a Revenue unit this month, as the impact of Alistair Darling’s planned tax rises on their behaviour attracts fresh attention.

The Institute for Fiscal Studies, an independent think-tank, will on Monday publish research ahead of the Budget showing how the government’s room for manoeuvre on taxing the wealthiest is limited by likely changes in their behaviour. It expects those with incomes of more than £150,000 ($221,854) to respond to the new 45 per cent tax rate in ways that will significantly reduce the extra revenues raised.