The review will report by autumn and will look at cases where individuals use deeds of variation to alter a will in order to pass bequests on to their children, thereby removing sums from their estate for IHT.

David Kilshaw, EY's head of private client tax, said: 'The Chancellor has announced his intention to review deeds of variation to ensure they do not foster tax avoidance.

'However, deeds of variation are not just tax planning vehicles. They can ensure estates pass as families’ wish where there is no will or where circumstances have changed.

‘When somebody dies without a will, for example, a deed of variation may ensure a widow/widower can stay in their home. 

'Over two thirds of people don’t have a will - a deed of variation can be a lifeline for their heirs and it’s vital that any anti-avoidance measures don’t remove this.'

In making the announcement Osborne said the review will take ‘a wide range of views’, including that of the leader of the opposition. The issue was last reviewed in the mid-1980s but at the time the plan was shelved.

However, there were warnings that the measures could backfire as these deeds are not usually seen as a tax avoidance vehicle but allowed some level of flexibility for the bereaved.

Kingston Smith tax partner Lynne Rowland said: ‘Taxpayers need to ensure that their will reflects their up to date wishes.

‘Too often taxpayers have ignored changes in circumstances in the knowledge that their beneficiaries have the ability to amend their will up to two years after their death.

'This has been proposed previously and quietly dropped but it sounds as though it might be taken forward this time.’

Depending on the outcome of the election, it is possible that abolition of variations to wills may be pushed through quickly.

‘Families exposed to inheritance tax will need to ensure their wills are tax efficient now. Variations to wills may be disallowed within months,’ said Frank Nash, senior tax partner at Blick Rothenberg LLP.  

Dermot Callinan, tax partner, UK head of private client, at KPMG said: ‘There are many cases where variations are used simply to correct tax mistakes or use business and agricultural allowances on death, where a widow and other family members of the deceased want to make a change so that the estate can go to somebody else.

‘Without deeds of variation (DOV), executors will have to resort to the Courts who will become busier with “mistake” applications along the lines of the cases of Pitt-v-Futter and negligence claims against family solicitors.

‘It is a shame that something that has been around for generations to enable the straightforward handling of estates between families has been questioned as a mechanism for tax avoidance.’

Some saw the announcement as a cheap political jibe at the opposition rather than a concrete policy wish. Earlier this year Ed Miliband was revealed to have used a deed of variation to pass on a family property on his father’s death.