The proposed High Value Council Tax Surcharge is already influencing property transactions around the £2 million threshold, with evidence of increased sales activity just below the proposed band. For high-value property buyers and borrowers, the interaction between the agreed purchase price, lender valuation, and future Valuation Office assessment could affect both financing and transaction timing.

Between December 2025 and July 2026, 25 homes in England sold for exactly £2 million. In the same eight months a year earlier, 117 did. Over the same period, completed sales in the £10,000 band immediately below £2 million rose from nine to 21.

Those figures come from Tax Policy Associates' analysis of Land Registry data, published on 22 September. The analysis provides evidence that the High Value Council Tax Surcharge, sometimes referred to as a mansion tax, is shaping transaction prices close to the threshold before the charge itself begins in April 2028. Tax Policy Associates found a significant increase in sales just below £2 million, while cautioning that it has not yet found evidence of a wider fall in property values. Tax Policy Associates

The surcharge was announced in the November 2025 Budget and is due to take effect in England from April 2028. Under the current published structure, homes valued between £2 million and £2.5 million will attract a £2,500 annual charge, rising through bands of £3,500 and £5,000 to £7,500 for properties above £5 million. The relevant property valuation is based on 2026 values. The incentive to agree a price a few thousand pounds below a band boundary is therefore clear, and the available transaction data suggests some buyers and sellers have responded to it.

The threshold itself may now move. The Times reported on 20 September that lowering it to £1.5 million was a "live discussion" in the Treasury ahead of the Budget on 28 October. The reported change would substantially increase the number of properties potentially in scope. The Treasury's position is that tax decisions are announced at fiscal events, and no decision to lower the threshold has been announced.

Knight Frank has estimated that a £1.5 million threshold would also substantially increase the number of homes sitting in the valuation "grey area" close to a band boundary, from 73,600 to 222,800. Knight Frank

The detail that matters most for borrowers has had less attention. The Government's consultation says the Valuation Office will use the comparable method, looking at sales prices of similar properties and adjusting for differences between properties. It will draw on its property database and other sources rather than relying solely on the price achieved in an individual sale. A completion at £1,995,000 is therefore evidence that may inform the assessment, but it does not by itself determine which surcharge band the property falls into. HM Treasury

Islay's View

The mortgage lender, meanwhile, instructs its own valuer for its own purposes. A buyer can therefore end up with three figures for one house: the agreed price, the lender's security valuation and, in time, the Valuation Office's assessment. None is required to produce the same figure. Where a price has been negotiated to sit just below a threshold, a different interpretation of the comparable evidence could affect the lender's valuation and therefore the amount it is prepared to lend. The resulting funding shortfall would need to be met by the buyer before completion. That is execution risk rather than simply tax risk, and it is the part of this we most often see underestimated at Enness.

The charge itself also needs to be kept in proportion. Standard residential stamp duty on a £5 million purchase is £513,750, while the highest current annual surcharge is £7,500. For many buyers at that level, the annual charge is a holding cost to model rather than the central factor determining whether a transaction proceeds. The greater planning issue is the uncertainty around the threshold and bands ahead of the 28 October Budget, particularly for anyone buying, refinancing or raising capital against a property around the £1.5 million to £2.5 million range.

There is also a second open question for international owners. The Treasury's consultation, which closed on 14 July, asked whether non-UK resident owners should pay a premium on top of the surcharge. No outcome has been published. For overseas buyers, any future premium would sit alongside the existing non-resident stamp duty surcharge in the overall holding-cost calculation.

The longer-term effect may ultimately be felt through transaction volumes rather than simply headline prices. Tax Policy Associates has found evidence of bunching below the £2 million threshold, but not yet a measurable wider decline in property values. If buyers become more reluctant to cross a surcharge boundary, properties close to a threshold could take longer to sell even where the underlying value has not materially changed.

That distinction matters where property finance is involved. Anyone relying on a sale near a band boundary to fund an onward purchase or repay a bridging facility should consider timing as well as price when assessing the exit. A slower sale can create financing pressure even where the eventual achieved price remains broadly consistent with expectations.

For borrowers, the key issue is therefore not simply whether a property falls above or below a particular tax threshold. The agreed purchase price, lender valuation, available borrowing and eventual Valuation Office assessment can all play different roles. The closer a property sits to a band boundary, the more important it becomes to understand how each figure could affect the overall transaction before committing to the purchase or relying on a particular financing structure.

Important Information

This article is for general information only and does not constitute financial, tax or legal advice. Enness Global does not provide tax advice; speak to a qualified tax adviser about your own position. Proposals described as "reported" have not been confirmed by the Government. Figures are taken from the third-party and Government sources named and are correct at the date of publication.

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