IHT boom forecast for Cambridge and Oxford

The findings are based on a Freedom of Information request to HMRC and form part of a wider analysis covering 177,000 estates across all 121 UK postcode areas.

In the Cambridge postcode area (CB), the number of IHT-liable estates is projected to reach around 410 by the end of 2026/2027 – up from 248 in 2021/22.

The area’s total annual inheritance tax liability is set to rise to £97 million, equating to an average IHT bill per estate of £237,000

Oxford’s postcode (OX) is forecast to see almost 630 families affected by IHT each year by the end of 2027, a sharp increase from 399 in 2015/16. The total IHT liability is predicted to grow from £72m in 2015/16 to £153m over the same period.

Andrea Jones, National Head of Irwin Mitchell’s Private Client Advisory team, said: “These figures highlight the growing impact of inheritance tax on families in Oxford and Cambridge. With liabilities rising sharply, it’s more important than ever for individuals to seek expert advice. Proactive estate planning can make a significant difference in protecting wealth for future generations.”

The report also highlights the impact of upcoming reforms to Agricultural Property Relief (APR) and Business Property Relief (BPR), which will take effect from April 2026.

These changes will cap full 100 per cent relief at £1 million for combined qualifying assets, with amounts above this threshold receiving only 50 per cent relief. AIM-listed shares will also see reduced BPR eligibility, potentially increasing the number of estates liable for IHT.