HMRC is set to send valuation agents to properties across the UK to determine whether homeowners fall under the new High Value Council Tax Surcharge.
The taxman’s inspectors will have the power to demand entry to properties in order to assess whether they are worth over £2m and therefore subject to the levy.
The charge, commonly referred to as the mansion tax, was first introduced by former chancellor Rachel Reeves in last year’s autumn budget and is due to take effect in April 2028.
A consultation on the new levy ended in July, paving the way for the surcharge to be applied to eligible properties within a matter of years.
The charge will apply to properties worth over £2m, with an extra annual levy of between £2,500 and £7,500 depending on the value of the property in question.
Homeowners who refuse to allow inspectors entry may face fines of up to £200 and could be committing a criminal offence, according to The Telegraph.
To identify which homes are subject to the charge, valuation agents will draw on third-party data and publicly available information to estimate property values before determining whether an inspection is required.
The Valuation Office, the part of HMRC responsible for maintaining council tax bands for homes in England and Wales, says inspections will be required where “attributes can only be confirmed internally or a re-measurement is required.”
Inspectors will assess property interiors, looking at factors including size, architectural style, number of bedrooms, bathrooms, and storeys when conducting their valuations.
The mansion tax charge is expected to affect 165,000 homeowners during its first year, a figure significantly higher than the 120,000 originally forecast by officials.
That means a surplus of 45,000 homes will be drawn into the levy compared to initial projections, according to the fiscal watchdog, though thousands of homeowners are expected to be able to successfully appeal the tax.