The new High Value Council Tax Surcharge, announced in the November 2025 Budget, could leave some families with an additional tax bill to settle from an estate under proposals from the government.
The government published its consultation on 19 May 2026, setting out some of the potential structure for how the so-called ‘mansion tax’ would work in practice.
The tax is expected to operate as an additional levy on homes worth more than £2 million, with an annual charge of up to £7,500 depending on the property’s value.
One of the main early criticisms of the levy was that many homeowners could be ‘asset rich but cash poor’: they may own high-value homes but have modest incomes, making it difficult to meet the additional council tax charge from regular cash flow.
The government has proposed that, where household income is below £35,000 a year, the levy may be deferred until the property is sold, transferred or otherwise changes ownership.
In practice, this could mean the deferred charge becomes an estate planning issue, as the accumulated liability may need to be settled when the property is sold or transferred after death.
The proposed tax has also been criticised as potentially expensive to administer. The government has indicated that revaluations would need to take place every five years to ensure homeowners are paying the correct amount under the levy.
Estate agents such as Hamptons have already warned that the proposals are starting to influence pricing, with some properties around the £2 million mark seeing discounting as sellers and buyers seek to remain below the threshold.
Estate agents such as Hamptons have already warned that the tax proposals are starting to influence pricing, with properties for sale around £2 million beginning to see some discounting to keep the price below the threshold.
Commenting, the report author David Fell wrote: “The Mansion Tax introduces an additional layer of financial commitment for prospective buyers, and its influence is already beginning to shape behaviour and create a cliff-edge.
“Looking ahead, this is likely to encourage some degree of price bunching around the tax thresholds, with a higher share of purchases completing just below as buyers seek to avoid triggering the tax for at least until homes are revalued.”
Planning considerations for high-value homeowners
Anyone with a home in this value range should consider how the proposed surcharge could affect their cashflow, income needs and wider estate planning. However, it is important not to make any knee-jerk decisions to the tax changes. Instead, speak with your Insight financial adviser who will help you understand your options and give solutions for how to best structure your long-term plans, preserve financial stability and anticipate potential tax liabilities.
If you own a high-value property and are concerned about how the proposed surcharge could affect your estate planning, please get in touch.
Sources and further reading:
Cost-of-living and mental health | Mental Health Foundation
The Facts – updated 2024
Mental Health Awareness Week | Mental Health Foundation
Disclaimer: information is based on publicly available data and government announcements at the time of writing (May 2026) and may be subject to change.