Revenue collected from inheritance tax (IHT) between April 2021 and January 2022 totalled £5 billion, £0.7bn higher than in the same period a year earlier.
IHT receipts were 16% higher during the period, which HMRC predicts is due to higher volumes of wealth transfers caused by the COVID-19 pandemic.
HMRC said it cannot verify this claim until full administrative data becomes available, however.
Andrew Tully, technical director of insurance company Canada Life, said rising house prices also contributed to the growth in IHT receipts.
In March 2021, the Treasury froze the nil rate band and residence nil rate band thresholds at £325,000 and £175,000 respectively until 2025/26.
According to Shaun Moore, tax and financial planning expert at Quilter, the freeze and rising house prices could lead to more people facing a "hefty" IHT bill.
He added the complexity of the UK's IHT system is overly complex and makes it difficult to plan for - particularly the residence nil-rate band.
He said:
"Perhaps now is time for a rethink of IHT to make the regime as easy to understand as possible for IHT payers."
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