HMRC to send inspectors into £2m homes under new mansion tax

HMRC announced it will dispatch valuation agents to homes across the United Kingdom to determine whether owners should pay the new High Value Council Tax Surcharge, commonly called the mansion tax. The inspections aim to identify properties valued above £2 million, the threshold that triggers an annual levy of between £2,500 and £7,500.

How the inspections will work

Agents will be authorised to enter premises and measure interior dimensions, count bedrooms, bathrooms and storeys, and assess architectural style. They will also draw on publicly available third‑party data to estimate market value. The Valuation Office, which maintains council tax bands, says entry will be required when internal attributes cannot be confirmed or a re‑measurement is needed.

"Refusing entry is a criminal offence and could result in a fine of up to £200," reported The Telegraph.

Impact on homeowners

The levy, first outlined by former chancellor Rachel Reeves in the autumn budget last year, is slated to start in April 2028 after a consultation closed in July. Early estimates expected 120,000 homes to be affected; the fiscal watchdog now projects about 165,000 properties will face the charge in the first year, adding roughly 45,000 more than originally forecast.

Property owners who decline access risk a £200 fine and a criminal record. Many will likely appeal, and the volume of cases could test the capacity of the tax authority’s dispute system. The broader fiscal context, including recent borrowing trends, suggests the government is seeking steady revenue streams ahead of the next election cycle. For a deeper look at the tax policy outlook, see our analysis of the Treasury’s approach here.