Prime Minister David Cameron has pledged the Conservatives will create a new threshold for inheritance tax of £1m if elected.
The changes would come into effect from April 2017, and will be funded by restrictions on pensions tax relief for those earning more than £150,000.
Annual allowances for savings will be tiered on earnings between £150,000 and £210,000, with those earning £210,000 seeing their annual allowance cut from £40,000 to £10,000.
In a speech this weekend, Cameron said the individual IHT threshold will be raised from £325,000 to £500,000 when property is included, giving a married couple a shared £1m threshold.
Reduced allowances will be offered for properties worth more than £2m, with those worth upwards of £2.35m seeing no change.
The Conservatives claim around 22,000 families will benefit from the move by 2020.
Cameron said: “We will take the family home out of inheritance tax. That home that you have worked and saved for belongs to you and your family.
“You should be able to pass it on to your children. And with the Conservatives, the taxman will not get his hands on it.”
The Conservatives pledged to raise the limit to £1m in their 2010 manifesto, a move blocked by the Liberal Democrats in coalition.
But the Institute For Fiscal Studies says the change would “disproportionately” benefit those on higher incomes.
It says: “Since the children of those with very large estates are disproportionately towards the top of the income distribution the gains from this (and in fact any) IHT cut will also go disproportionately to those towards the top of the income distribution.”
Labour also plans to reduce pensions tax relief for those earning over £150,000.