HMRC has increased the amount of extra tax it brings in through challenges to property valuations submitted by estates for Inheritance Tax (IHT) purposes by 23% in the last year, according to research by UHY Hacker Young.

The firm's analysis showed HMRC brought in an additional £108m through such challenges in the 2012-13 tax year, up from £88m in 2011-12 and £70m in 2010-11. It says HMRC is now taking a 'pretty aggressive' approach and making more frequent challenges to the figures.

In cases where HMRC was successful in arguing for a higher valuation for a property, it raised an average of £34,704 in additional tax, up from an average of £27,227 in 2011-12.

Mark Giddens, UHY Hacker Young partner, said: 'With house prices set to rise further in the coming year, that will push more properties above the minimum threshold, it is likely that IHT will continue to be a lucrative area for HMRC to focus on.'

UHY Hacker Young says that HMRC now checks Land Registry records of the sales of other properties in the area when they receive an IHT return and investigates whether there have been any refurbishments or extension to the property that might have increased its value, but have not been taken into account.

Giddens said: 'HMRC might also challenge a property valuation if it seems low relative to the price that the deceased paid for the property. However, this ignores the possibility that the deceased overpaid for the property in the first place or maintained it poorly.'

The government has recently signalled it intends to keep up the pressure in this area, with an announcement in the Autumn Statement that it expects to receive £21.4bn in IHT between 2013/14 and 2017/18, an increase of 16.5% compared to its estimate in the Budget eight months earlier, UHY Hacker Young pointed out.