George Osborne has said estates will benefit from a 10% discount in inheritance tax (IHT) if they leave part of the money to charity, though the cut translates to just a 4% reduction in the final bill.
IHT is currently charged at 40% on estates worth more than £325,000, the nil-rate band, following their owner's death. It is also levied on assets transferred in the preceding seven years.
But the 10% discount is taken off of the current 40% tax rate, meaning an actual reduced tax rate of 36%.
The nil-rate band can still be transferred to the surviving spouse, creating a combined tax-free allowance of £650,000.
Darling froze this threshold for four years in March 2010's budget.
Two global vehicles
'Further plug advice gap'
Must appoint separate CEOs and boards
Advisers do come out well
Will report to Mark Till