Band 1
£2m – £2.5m
£2,500
per year
One five-year cycle
£12,500
'Mansion Tax'is coming
Powered by the Valuation Evidence Engine
Could your home be allocated to aHigh Value Council Tax Surcharge band?
Bands will be based on your home's 2026 value until 2033, so an overvaluation means you pay more tax than necessary for several years. Our Engine lets you check your property's potential band now, and produces evidence that could support a future challenge.
Free to check · Optional detailed Evidence Appraisal £99
The four surcharge bands
Know your bands.
Under the government’s current proposal, the annual surcharge is set by your property’s 2026 value and added alongside council tax from April 2028. A small change in valuation can move a home into the next flat-rate band.
Band 2
£2.5m – £3.5m
£3,500
per year
One five-year cycle
£17,500
Band 3
£3.5m – £5m
£5,000
per year
One five-year cycle
£25,000
Band 4
Over £5m
£7,500
per year
One five-year cycle
£37,500
Actual liability will depend on the final policy, ownership and any successful challenge. Read the government consultation for more. Also see our Timetable for details on implementation and challenge schedules.
Valuation Evidence Engine
How the Evidence Engine works
The Valuation Office will begin provisionally allocating homes to 'Mansion Tax' bands in late 2027.
The aim of the Engine is to provide the most balanced band appraisal the facts allow (using data the Valuation Office may not account for) to assist clients in edge cases and potential disputes.
Try it for Free - The Engine will generate your property's estimated band and Valuation Range for free. If you wish, you can then commission a 2026 Property Evidence Appraisal to record the data and weighting behind those calculations, which can be used to support a future challenge to the Valuation Office.
Learn more about why we built the Engine here.
Your Evidence Engine assessment
Check your potential band
- Enter postcodeStep 1 of 4
- Choose addressStep 2 of 4
- Review propertyStep 3 of 4
- Add conditionStep 4 of 4
Takes around 3 minutes. No payment details.
Stage 1 · 2026 Property Evidence Appraisal
Record your 2026 position
As the new levy is based on data sets - just like Council Tax - it is not pricing your home or assessing what a buyer might pay. It is therefore sensible to record any evidence that could justifiably support a reduced (or nil) tax position.
Our 2026 Evidence Appraisal helps with this. The Appraisal breaks down the local trends, index adjustments and comparable data behind the Engine's free calculations, to provide you with the evidence that may support a future banding challenge.
£99fixed fee
It can be refreshed and updated for free at any time.
This purchase does not include a challenge, representation or legal advice. Orders placed under earlier terms retain the benefits promised when they were purchased.
What's included
A concise, evidence-led appraisal
- Named completed-sale schedule
- Recorded property facts
- Local trend and date adjustments
- Indicative Value and Valuation Range
- Evidence-confidence assessment
- Source references and dates
After official banding
Challenge Pack for Self-Submission · £199
After your home's official band has been released, we will let you know if it appears inconsistent with your Appraisal. If a challenge to the Valuation Office is supportable, you can purchase our solicitor-written covering letter, outlining your grounds for challenge by reference to relevant legislation, the available evidence and RICS valuation principles.
The covering letter will be editable for you to check, add your own facts and photographs, and submit yourself.
Assessment updates
Keep up with all things Mansion Tax.
Leave your details and we’ll tell you when the draft band list arrives, when the formal challenge window opens and when it is due to close.
FAQs
Clear answers,before you begin.
What is the Valuation Evidence Engine?
It is our proprietary technology for combining trusted property data, completed comparable sales, local market trends and your home’s condition into a structured evidence picture.
Why prepare evidence now if I cannot formally challenge until 2028?
Because the proposed bands are based on 2026 values. A dated record of the property facts, condition and completed-sale evidence is stronger than trying to reconstruct the 2026 position later. The £99 appraisal records that evidence now; any later self-submission product is separate.
What do I receive for £99?
A personalised 2026 Property Evidence Appraisal showing the named completed sales, adjustments, evidence range, confidence and limitations behind the Engine result. It records your 2026 position and can be refreshed and updated free of charge; it is not a challenge submission.
What happens after official bands are published?
If an official band appears inconsistent with the appraisal, we intend to offer a separate £199 Challenge Pack for Self-Submission. It would provide updated evidence and an editable solicitor-written covering letter for you to complete and submit yourself. It is not yet available, and Mansion Tax Checker would not represent you or give individual legal advice.
Will I need a Red Book valuation?
The Government’s current Mansion Tax consultation does not say that every challenge will require one. Comparable completed sales and verified property facts are central to the proposed approach. Limited evidence is reflected in the Engine’s confidence score and Valuation Range. A confirmed material property characteristic that the model cannot reliably capture may instead trigger an independent Red Book valuation recommendation.
Does Mansion Tax Checker provide a formal valuation?
No. Mansion Tax Checker is a technology platform, not a surveying firm. We analyse the evidence available and explain what it supports; the appraisal is not a RICS Red Book valuation.
Will a Mansion Tax Checker assessment guarantee a lower band?
No. We never promise an outcome. Our role is to assess the evidence objectively and help you understand how it compares with an official band when one becomes available.