A feature of recent Budgets is the announcement of tax changes that are deferred for several years. The changes to IHT on business and pensions are a good example. So too is another directed at wealth: the high value council tax surcharge (HVCTS), aka mansion tax.
Full details still awaitedâŚ
The Autumn 2025 Budget announced that the new tax would come into effect from April 2028, for properties valued at least ÂŁ2 million in 2026 (with no specific date given). Despite the reference to council tax in the name, HVCTS will go into the governmentâs coffers, with council involvement limited to collecting the new tax alongside council tax and passing it on. A consultation document was promised âearly in 2026â, but by mid-April none had arrived. However, we do know the rates:

OBR insight
The lack of consultation did not stop the OBR from publishing its thoughts on the impact of the new tax, which included:
- By 2028, the capitalized value of the surcharge would be fully reflected in property prices. This would imply a reduction of about ÂŁ35,000 per ÂŁ1,000 of surcharge, based on the OBRâs assumed inflation rate of 2% and a discount rate of 5%.
- Prices will bunch just under the various HVCTS thresholds, just as happened when the stamp duty rate was based on property values. There is already anecdotal evidence that this is happening.
- The band structure will encourage valuation appeals, which the OBR expects will apply to 20% of properties initially deemed liable. Four in ten of those appeals is forecast to succeed.
- The revenue raised by the HVCTS will be partially offset by lower stamp duty, capital gains tax and IHT because of reduced property values.