More than 14,000 investigations into families suspected of underpaying inheritance tax have been launched by HMRC since April 2022, a Freedom of Information (FOI) request found.
The FOI data also shows a sharp rise in the number of new inheritance tax investigations launched by the tax authority during the first nine months of this tax year.
In the current 2025/26 tax year alone, 3,636 probes have been opened, according to the figures obtained from HMRC by financial adviser NFU Mutual.
Start your trial of MoneyWeek today
Get unparalleled financial insight, analysis and expert opinion you can profit from.
Start your trial
Sign up for MoneyWeek’s free twice-daily newsletter.
Join more than 165,000 subscribers and keep yourself informed with latest financial news, insights and expert analysis to help you understand what really matters when it comes to your finances.
Join more than 165,000 subscribers and keep yourself informed with latest financial news, insights and expert analysis to help you understand what really matters when it comes to your finances.
These investigations – launched between April 2025 and December 2025 – account for almost a quarter of all IHT investigations opened since April 2022.
Latest Videos FromMoneyWeek
The number of new inheritance tax investigations into estates where the tax is suspected to have been underpaid jumped by 33% in the three years to April 2025 – from 3,163 in 2022/2023 to 4,200 in 2024/2025.
More families are set to be dragged into the inheritance tax net in the coming years which could lead to greater numbers of HMRC investigations into suspected underpaid IHT.
Inheritance tax is payable at 40% on anything inherited over the £325,000 tax-free threshold (also known as the nil rate band). If a home is being passed to children or grandchildren, then an additional £175,000 allowance is applied. Couples can combine their allowances to pass on a total of £1 million tax-free.
Sean McCann, chartered financial planner at NFU Mutual, said: “IHT remains one of the most feared and least understood taxes, with unspent pensions falling within the inheritance tax net from 2027 and many farms and businesses from April 2026, more and more families will find themselves dragged into paying inheritance tax.”
The Office for Budget Responsibility (OBR) has forecast that 9.5% of deaths could trigger inheritance tax bills by 2029/30 up from 5.1% in 2022-23.
Fresh figures from HMRC show IHT receipts collected between April 2025 and January 2026 jumped by £130 million compared to the same period in the 2024/25 financial year, rising to a total of £7.1 billion in the first 10 months of the current 2025/26 tax year, as more families part with some of their inheritance.
An HMRC spokesperson said: “Most people pay the correct amount of Inheritance Tax. In cases where it is suspected someone has not, investigations can be opened to address issues and ensure the system remains fair.”
How does HMRC investigate inheritance tax?
HMRC has substantial investigatory powers and will check a range of sources to build a picture of the deceased individual’s financial affairs where there is a suspicion inheritance tax has been underpaid through error, omission, or undervaluing assets, said McCann.
This can include analysing bank statements to identify income which may suggest the existence of undisclosed assets such as investments or property or significant foreign currency transactions.
McCann added: “HMRC leaves no stone unturned in these investigations.”
For example, they will look at outgoings such as gifts made in the seven years before death, or premiums for life insurance policies which if not written in trust will form part of the taxable estate.
“The revenue recovered through these investigations is significant and the rising value of assets and the potential sums at stake would appear to justify HMRC increasing the number of cases they look at. The increased level of information available to HMRC also allows them to be more forensic and targeted in nature,” McCann said.
Furthermore, the interest rate you pay on overdue inheritance tax stands at 7.75 % which can add a significant amount to the bill. This can compound what for many is already a challenging and distressing situation.
“With the £325,000 nil-rate band and the £175,000 residence nil-rate band frozen until 2031, more families will be caught in the inheritance tax net with ever increasing bills for those affected,” McCann added.
