Expert Witness Valuation Reports
Challenging the ‘Mansion Tax’
High Value Council Tax Surcharge
Announced by Chancellor Rachel Reeves at the Autumn Budget in 2025, a High Value Council Tax Surcharge on homes in England worth £2 million or more will be payable by the owner of the Property. It will take effect from April 2028 but will be based on the value of the property in 2026.
Property Value Surcharge
£2m - £2.5m £2,500
£2.5m - £3.5m £3,500
£3.5m - £5m £5,000
£5m+ £7,500
You will need an Expert Witness Valuation Report valuing the Property in 2026, to stand the best chance of challenging the Surcharge. Our Reports will be caried out by Robert Kaye MSc MRICS who is an RICS Registered Valuer with 20 years of experience. Robert regularly undertakes Expert Witness Valuation Reports on London properties and appears as an Advocate and Expert Witness at Courts and Tribunals. Robert is well placed to act on your behalf to Appeal your case, if required.
HHJ Baucher in a recent Judgement stated ‘…..Mr Kaye was an impressive witness….. In keeping with the careful manner in which he prepared his reports and the joint statement, I found he presented his evidence in a similar manner…….I found his evidence on all issues to be clear, logical and compelling. It was tendered in a measured fashion. I have no hesitation in accepting Mr Kaye’s evidence in its entirety.’
To know your likely Surcharge and be in a position to make an early Appeal, contact us now for a quote for an Expert Witness Valuation Report. Email:
How much will you pay and will you be able to challenge it?
Our Report will give you a reliable value of your Property to ascertain which Surcharge will be relevant. Crucially the Report can be used to challenge the Valuation Office Agency assessment. Commissioning a Report now will give a reliable record of the size, condition and value of the property in 2026.
Not all valuations are equal
Appealing your Surcharge will likely be done via the First Tier Property Tribunal or Valuation Tribunal Service and will be based on the value of the Property in 2026.
An estate agent or chartered surveyor report is unlikely to carry any weight with a Tribunal. The Valuation Report will need to comply with Part 35 of the Civil Procedure Rules (an Expert Witness Valuation Report). The duty of the valuer is to the Tribunal or Court. Our Reports contain a detailed description and floor area of the Property, well presented comparable evidence, market commentary, clear explanation of the methodology and the required Part 35 Statements. An Expert Witness Valuation Report is the ‘gold standard’ of valuations.
Potential Issues
The relatively narrow Surcharge bands will lead to a very high level of Appeals. The tolerance for RICS Valuations on high value residential property is wide and this leaves the Valuation Office Agency (VOA) open to challenge.
How will the VOA correctly value leaseholds as part of a mass valuation exercise? If your Property is leasehold we will take account of the terms of the lease in our Valuation.
The Mansion Tax is likely to push down property values around each Surcharge boundary. This will be reflected in our Valuation.
We expect there to be a huge amount of Appeals. The government estimates there are 100,000 Properties which will be hit with the new Tax. Currently the wait time for an Appeal to challenge a Council Tax band is circa 12 months. The wait time is likely to far greater if you wait until your Surcharge is announced (likely to be late 2026/early 2027). By commissioning your Report now, there will be no delay if you wish to lodge an Appeal.