Tax specialists and wealth managers regularly charge that the Residence Nil Rate Band (RNRB) introduced in 2017 has made UK inheritance tax almost impossible to navigate and therefore easier to infringe.
Data obtained recently through a freedom of information (FOI) request has found that roughly 5,000 IHT investigations are opened by HM Revenue & Customs each year, a rise of around 8 per cent since the RNRB allowance was introduced. Of 22,000 estates liable for IHT in the 2018/2019 tax year, a quarter are being investigated, according to data published by investment manager . 
Earlier this month the Office of Tax Simplification (OTS) released long-awaited recommendations on how to reform the tax code, including shortening the seven years gifting rule to five years, abolishing taper relief on gifts made more than three years before death, and combining lifetime gift exceptions into a single allowance. But the independent body fell short of suggesting an overhaul of the baffling rules surrounding IHT that have left some specilists admitting that they are unable to advise clients. It concluded that it was too early to revise the nil rate band as it hasn't been in force long enough to assess. It did, however, say that it would be better to abolish it and replace it with a higher universal nil-rate band, reiterating what many believe.
As it stands, individuals are liable to pay inheritance tax (IHT) at 40 per cent on any assets over £325,000 on their death. For married couples, or civil partners, any unused NRB can be transferred to the surviving spouse’s estate. This can increase the NRB to £650,000 on the second death. But that is where clarity generally ends, with numerous caveats on transfering property without penalty contingent on when and how it is gifted after death, how it was occupied, and so forth. WealthBriefing recently published a tax specialist’s guide to unpicking some of the opaque terrain. With a new administration under Boris Johnson already mooting wide reaching changes to UK tax laws, all eyes will be on what is feasible for IHT.
Quilter's tax and planning expert Gordon Andrews called the present system at times “deeply unfair” and needlessly complex. To add to this, “there is almost a one in four chance HMRC will investigate your estate,” and those being subjected generally aren’t "deliberately trying to defraud HMRC." Rather, they are just trying to navigate a complicated system.