Increased Council tax banding 40 years later

[Hectorsmother]

Posting on here for traffic.

We bought a house in October 2025 that had had an extension done in the 1980s.

For 40 years the house has been on band X, and we have continued to pay the same band for nearly 6 months. Council have written to say they have re-evaluated the property's value in 1994 and deemed it was worth more than they thought and therefore because of the sale we are now being moved up a higher tax band.

This feels utterly farcical and money grabbing from the council.

If there has been an extension on a house then the council can put an 'improvement marker' against that house. When its sold the council can then move the Council tax bracket up for the next person who buys the house. (You can check this pre-sale). It can be very random - I recently sold my house which 20 years ago had a large double storey extension - no marker. My neighbours had a utility room and downstairs toilet put in in the last five years and their house has an improvement marker against it.

I didn't even know there was a band X is it a mansion? you must be paying a fortune in council tax. My property is only band A and im paying a stupid amount on that.

Nothing about this marker was mentioned at the sale. What I find unbelievable is the time frame. The extension was done 40 years ago with the councils permission. I don't get why because they didn't evaluate it correctly on 1994 we NOW have to be at a higher band. Surely there has to be a statue on this sort of thing?

Why are we being told this nearly 6 months later with the threat that it will be applied to us retrospectively?

Presumably ready for the new tax year?

Oh no, I just picked it as an example. It is certainly not a thing and we certainly don't live in a mansion!!

This has just happened to us too We downsized last Summer and our bungalow was 2 bands below our previous large detached for council tax.
We got a letter recently as the sale had prompted rebanding. There’s been an extension since it was last reviewed. So now it’s just one band below our last house.

It just really hurts because it was already quite high and now they are going to squeeze us even more.

I feel so helpless and baffled.

Thank you for sharing. Out of curiosity what the time difference between the extension and the rebanding?

I am dreading you are going to tell me a 100 years!!

Yeah. It feels like they've gone how can we magic more money?
Pot holes everywhere.
Petrol prices going up and mortgage rates going up.

One thing that is NOT going up is wages. I despair.

I know i feel the same, i had anxiety when my latest bill came through the door and saw the increase yet again. And dont get my started on the huge increase in water rates. would probably be cheaper to have champagne coming out of my taps!

I didn't even know this was a thing. It's pretty shitty that this is not more transparent. In the area we're looking at, we're discounting anything above a particular tax band because the jump is too steep, but it sounds like you could end up paying that anyway?

For those voting I am being unreasonable - can you please tell me why?

im surprised checks weren't done by your conveyancer to check council tax banding was correct etc during the sale of the property.

Exactly! We looked at the council band for this house before we bought it as part of our budgeting.

What's quite uncomfortable is how far can the council go back to claw more money?

The Sale of the house would have triggered this. You would think this would come out in conveyancing! I only come across this when browsing a property forum. I was curious on my own house as knew it been heavily extended and checked it out. My late parents commented at the time that the Council can change CT at anytime if they think you have improved the property to move it into the next band.

If the property had an improvement notice, the council tax banding will only be reviewed at the point of sale. That’s why it can happen so much later. I would have thought the conveyancing should have identified it but not certain. You don’t know what you don’t know. I only know this as currently looking to buy a property with an extension and for whatever reason an improvement marker doesn’t seem to have been applied to it.

This is normal I’m afraid. Happened to me too after I bought my house. Very annoying - especially when no more bedrooms have been added.

I can see that this is normal to those in the know. But looking at it with outsider eyes am appalled.

I actually looked at this recently.
Yes, a house can be extended by its current owners and will not change bands but will then be reevaluated upon sale. Its in black and white on the government website.
You can try and get it rebanded but it will be done on its current size, so if its right then they probably wont budge.
I didnt know this either until I looked into it.

It's normal in the sense that they can only review the banding at point of sale, they couldn't have done it earlier as it simply isn't allowed.

The Value Office Agency (Govt department who assess banding) and Council haven't done anything wrong, but I am surprised it wasn't picked up by the conveyancer.

If you go on the VOA website and look at any house it will show if there's an improvement marker on. We have had a large extension and we have such a marker so if we sell it will be reviewed. But I know this due to a previous line of work, I don't imagine it's common knowledge and would have assumed your solicitor would pick it up.

Thank you that is helpful to know that this is how it is done..
My disbelief was more at the why is it this way angle.

No am afraid no one else has picked it up or remarked on it.
Nasty surprise when I opened that blue letterhead paper simply stating they are going to put it up based on values in 1994.

thats awful! just another money grab! what band will you be now?

I only looked into it as I was helping family out with a question as to why one family member who lives in a tiny two bed bungalow is paying the same band as the other family member who lives in a 5 bed 3 bath detached. I found out it was because the family member in the large house had extended their house extensively 40 years ago and then never moved.
I think they should put something on the sale information really. Rather than just state the current band.

I would have thought that when the solicitor carried out the searches, and found out that the property had been altered by the current owner/from the original deeds, then they would check to see if there is an improvement marker. Maybe not, but it seems a natural route for those in the know.

Banding reviews aren't carried out when improvements happen as houses change so much it would trigger 100s and 100s of thousands of requests a year, which is unmanageable, but I agree a buyer generally wouldn't have a clue and it should be spoken about in the sale process.