ChatGPT vs PB
Monday 28th September 2026
On Mansion Tax - No contest.
The new Mansion Tax is very much in the news.
I have zero doubt that this, or future Governments, will reduce the catchment from the currently proposed £2m to £1.5m soon, and then possibly £1m.
The cowardly politicians cannot bring themselves to properly review our rotten taxation system around property.
Regular readers will know that my preference is to drop SDLT to 1-3%, get rid of Council Tax and Rates altogether and bring in an Annual Property Tax of 0.5% on all properties, payable by the owner.
Instead, we have this half-cock idea which they have the temerity to call high-value council tax surcharge (HVCTS).
Of course, it is not Council Tax at all plus it will largely fall on London.
The capital’s local authorities tasked with collecting this tithe will not see a penny beyond the admin charge to Govt. for collecting it.
Conniving civil servants in the Treasury have persuaded their muppet-masters another form of tax should be created, not as a replacement but as an extra revenue stream. You can be 100% certain they will push it down the value range as soon as they can.
The Valuation Office Agency (VOA) has been tasked with assessing the tax bandings.
Additionally, tasked with adjudicating contested rents under the Renters ‘Wrongs’ Act, something which will be incredibly time consuming, I can see more jobs for the boys/cost to the taxpayer.
Luddite that I am, I have just started using ChatGPT in earnest. It is a great tool for research, though it is imperative to question its’ thinking.
Last week I found myself in an ‘argument’ with the wretched thing over how much the collection of the Mansion Tax would cost the taxpayer.
It started with a mini essay outlining all the benefits, pulling on Govt and Guardian sources. Barely any negative comments.
Then ChatGPT suggested the cost of collection would be about 2% of the revenue raised. I was incredulous.
PB: ‘Really! Have you considered the cost of assessing all the properties and the contested borderline cases?’
ChatGPT: ‘You make a good point. I had not. The recalculated cost will be 4%.’
PB- again incredulous: ‘What % of borderline cases are you saying will be contested?’
ChatGPT: ‘20%.’
This is the point at which I remind myself that ChatGPT is not a relatively wealthy human used to getting their own way but a naïve algorithm designed with woke logic at its core.
‘Calculate it at 80%’, I say.
ChatGPT: ‘Yes. The cost of collection may be 10-15%.’
Getting into its stride it asked - ‘Would you like me to consider the fact that the bands have to be re-assessed every year?’
I agreed but quickly realised the question was ill-conceived because HVCTS will be re-assessed every five years and a property is stuck in a band even if it has actually fallen below in value, in part because of this very tax.
We have already seen a flat in Knightsbridge sell for £1,999,999 - just under the £2m threshold. Good effort by the buyer and their solicitor. Let’s see if VOA contest that figure as a contrivance.
One I did not ask ChatGPT but I ask you now ‘Who should pay for the surveyor costs of an owner if it is shown that VOA have over-valued a property into a higher band’?
At the moment, the conclusions from ‘consultation’ undertaken by Govt. on this whole HVCTS nonsense have not been published.
A rather surprising side effect of this debate with ChatGPT is, I find myself agreeing with Trump that a better term for AI may be SI - Super Intelligence. Not yet but soon.
Finally, if you are concerned about your London property potentially being over valued by VOA, I am happy to assess the current market price, so you can know where you stand so you can contest it, if they are wrong.
Bearing in mind that VOA is an arm of HMRC you can be sure they will up-value as much as they can.
Share your views with me please.
Until next time………
PB
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