Recent figures published by HMRC show IHT receipts have increased by 60% over the last five years - from £2.9bn in 2011/12 to £4.7bn in 2015/16 - according to Hargreaves Lansdown analysis.

Receipts have been increasing year-on-year since April 2009, when the IHT allowance was frozen. The £325,000 threshold for IHT to be paid has not changed since April 2009, and is not scheduled to be re-examined again by the Treasury until at least April 2019.

The Inheritance Tax income was a 17% increase in the last year alone, and a 91% rise on 2009-10, the year in which the IHT threshold was last raised, according to Wilsons, a private client law firm.

The most detailed stats, which related to the tax year 2013-14, showed:

• 417 estates owed more than £1m in Inheritance Tax. Of these 414 contained cash, 360 contained property and 395 contained securities (such as shares).

• Nearly 250,000 estates owed no tax at all as they did not reach the £325,000 threshold.

• London and the South East paid almost as much as the rest of country combined paying £1.6bn, while the rest of the country paid just over £1.7bn.

Wilsons said that the relative importance of IHT to HMRC has been increasing in recent years, as it now makes up 0.87% of all tax receipts in the UK, compared with 0.57% in 2009-10.

Former Chancellor George Osborne last year announced the introduction of an additional Residential Nil Rate Band, giving individuals the opportunity to pass on additional £175,000 of residential property to their direct descendants free of IHT by 2020. This, in effect, will raise the IHT threshold to £1 million for a married couple, so long as at least £350,000 of the estate comprises a primary residence.

Tim Fullerlove, Partner at Wilsons, said: “Inheritance Tax is gradually becoming a general tax on ‘Middle England’, and the longer it goes on, the harder it will be for the Treasury to let that income go.”

“With each passing year, more and more and more middle-class estates are passing the IHT threshold, and are being penalised by a tax that was never intended for them.”

He said: “The IHT threshold has now slipped more than £65,000 behind where it should be if it had kept pace with inflation. By 2019, the next point when the threshold might be increased, that gap is only going to have widened.

“The Residential Nil-Rate Band is a welcome boost for married couples looking to pass on the family home to their children, but it has left those without children, and those who do not own their own property, in the lower division of a two-tier inheritance system.”

HM Treasury said in a statement that the government wants families to be able to pass on their home to their children or grandchildren.

It pointed to reform of the rules to bring down the number of families paying inheritance tax from next year, with nearly 30,000 estates taken out of paying inheritance tax in 2020-21 alone.

Officials stated that under the new system families will have a new £175,000 inheritance tax allowance for their home on top of the existing £325,000 threshold – allowing them to pass £1 million onto their children completely free of inheritance tax.