The proportion of properties sold in England and Wales above the £325,000 Inheritance Tax (IHT) ‘nil-rate band’ is heading to a record high in 2016, according to new research carried out by Saga Investment Services.

Earlier this year, Saga found that 24% of properties sold in 2015 exceeded £325,000, an increase from 13% in 2009 when the nil-rate band was first set.

In new analysis of property sales data from the Land Registry for the first seven months of 2016, that figure has edged up to 26%, meaning more than one in four properties were sold over the nil-rate band.

Saga analysed data in 105 postcode areas in England and Wales and found that the biggest areas for growth were predictably in London. In central London, 82% of properties sold so far this year exceeded £325,000, up from 76% in 2015. 95% of properties sold in the EC postcode area for more than £325,000, marginally up from 94% in 2015. North London has seen a bigger jump, from 76% to 83%, while South East London has increased from 63% to 71%.

In addition to this, almost two thirds of properties in outer London were sold for more than £325,000 in the first seven months of the year, up from 55% last year. In Twickenham, Kingston, Bromley and Harrow, more than 70% of properties sold exceeded £325,000. For inner and outer London in total, almost three in every four properties sold (72%) in 2016 exceeded the IHT nil-rate band, compared to 65% in 2015, and 34% in 2009.

Overall, there has been a small rise in the proportion of properties sold for more than £650,000 – the maximum that can be passed on by someone who inherits any unused IHT allowance from their spouse or civil partner. Some 5.8% of property sales exceeded £650,000, up marginally from 5.4% in 2015, and more than double the 2.4% of properties sold in 2009.

33% of properties sold in central London exceeded this amount, up from 30% last year. One in five properties across 11 postcode areas were sold for more than £650,000. This has risen from just three postcode areas in 2009.

The findings come six months before the government introduces a new IHT allowance for people passing on their main home to a direct descendant. In 2017, an individual will be able to pass on £425,000 to their heirs, if this includes their main residence, meaning a married couple or civil partnership could pass on as much as £850,000. This new allowance will rise by £25,000 each year until it reaches £175,000 in 2020, when a potential £1m can be passed on. See notes to editors for more details on the main residence allowance.

Gareth Shaw, head of consumer affairs at Saga Investment Services, said: “The latest figures suggest that 2016 will be a record year for property sales exceeding the IHT nil-rate band. And with more people dragged into the IHT net simply because their property has risen in value, the tax is no longer just an issue for the wealthy.

“The main residence allowance will give this group of people in a property hotspot some welcome relief, but the rule will introduce more complexity to the already-confusing UK tax landscape. For anyone who believes their estate may be subject to IHT, early action with a professional financial planner will be a valuable investment.”