In British English the building attached to or beside a house is usually spelled "annexe" (a noun), while "annex" is mainly the verb meaning to add or attach something, and the usual spelling in American English. For planning and council tax, what matters is not the spelling but whether the accommodation stays ancillary to the main home or counts as a separate dwelling, as explained below.
What Counts as an Annexe in Planning Terms?
In planning terms, an annexe is accommodation that remains ancillary to the main dwelling. It exists to support the household living in the main property rather than functioning as an independent home.
The annexe might be attached to the house, connected internally, or completely separate with its own external entrance. The physical arrangement matters less than the relationship between the annexe and the main house. A granny flat built onto the side of a house would typically count as an annexe, as would a converted garage with a kitchenette and shower room used by an elderly relative.
Problems arise when the distinction between an annexe and a separate dwelling is unclear. Local Planning Authorities scrutinise proposals that could result in what is effectively a new house, even if the applicant calls it an annexe. If the accommodation has all the features needed for independent living and appears designed for occupation unconnected to the main property, planners may treat it differently.

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When you apply for planning permission, the council considers several factors to decide whether your proposal creates ancillary accommodation or a separate dwelling.
Size is one consideration. An annexe rivalling the main house in floor area may raise questions about its intended use. The level of facilities also matters: a basic bedroom with an en suite reads differently to a fully equipped property with multiple bedrooms, a large kitchen, separate living spaces and its own garden area.
Physical separation plays a role too. An annexe connected internally to the main house tends to appear more clearly ancillary. A detached building at the far end of the garden with no functional connection can look like a separate house waiting to happen.
Planners will also think about future use. Even if your current intention is to house a family member, the council may consider whether the building could easily be sold off or let independently. Some authorities attach conditions restricting occupation to family members or preventing separate sale. Check your local planning authority's policies before submitting an application.
Your situation may be slightly different. ask a question below ↓ and our editorial team will reply with our advice.
Council Tax and Annexes
Many people assume an annexe only attracts separate council tax if it has its own front door and appears completely independent. This is not how the system works.
The Valuation Office Agency decides how properties are banded. Their assessment focuses on whether the annexe could be let or sold separately, considering both physical characteristics and any legal restrictions. An annexe sharing essential facilities with the main house will usually remain part of the same assessment. But an annexe with full self-contained facilities may receive its own band, regardless of internal access to the main property.
Annexes occupied by certain relatives may qualify for a discount or exemption. GOV.UK provides information on council tax exemptions that may apply. If you disagree with a decision to band an annexe separately, you can challenge this through the Valuation Office Agency within set time limits.
When an Annexe Becomes a Separate Dwelling
Creating what is legally a new dwelling requires planning permission for a change of use, regardless of whether any building work takes place. Planning permission and building regulations approval are separate processes: satisfying one does not satisfy the other.
Signs that an annexe has crossed into separate dwelling territory include:
- Occupants have no family connection to the main household and pay rent
- The annexe is marketed as a rental property
- No shared use of facilities between annexe and main house
- The annexe has its own utility meters and separate postal address
- Occupants operate with complete independence from the main property
No single factor determines status: the overall picture matters. If multiple indicators point towards independent occupation, the planning authority may decide a material change of use has occurred. Penalties can include enforcement notices requiring you to cease unauthorised use, and failure to comply is a criminal offence.
Before starting work, consult your local planning authority. Most councils offer pre-application advice for a fee. Check whether permitted development rights apply, but note these can be restricted in conservation areas or Areas of Outstanding Natural Beauty. Even if an outbuilding falls within permitted development rules, using it as habitable accommodation may still require planning permission.
Keep records of permissions granted and conditions attached. The Planning Portal provides detailed guidance, and GOV.UK has information on council tax and the Valuation Office Agency.
The council then treated as such. Separate council tax status.
Mum still lives in it, she is now 93 years old.
We want to know if when she passes away, we will be liable for inheritance tax on it and as well as the main house.
We want to know if we can change it from being classed as an annexe back to being a house extension before that happens.
Can we call it an house extension?
She insisted on having a separate address which sparked a visit from the local council who immediately slapped a council tax bill on it and deemed it separate albeit nil rated as she was a dependent relative.
Now we have a potential buyer for our house who is being refused a mortgage and want the house to be returned to one address. Is this a possibility and if so what do we do.
The VO have say “We have split the title” the building from the main house and now the garage has a class T exemption.
By doing this the VO now say they have the right to revalue my main house. However I own the main house but the land the garage sits on I don’t own and was allowed to obtain the permission for the garage and gym etc and build at my own cost. The land is owned by my parents and has been since 1997.
The splitting of the “title” has trigged the revaluation of my property even though a sale hasn’t taken place. Can I stop the revaluation?
Regards
Robert
I have put a bed setee in it but there is no separate bedroom. It adjoins the garage with access to be able to get out. It also has french windows.
Would I need permission for anyone to stay overnight?
Kind regards.
. The proposed residential/ business accommodation/annex development hereby approved shall only be occupied and be used as ancillary accommodation to the main dwelling known at the time of decision as ....our address.....and at no time be subdivided from the curtilage of, or used as an independent unit of residential/business accommodation separate from .....our address...
So we know we are the only ones to uses it, we know we cannot separate it. It will contain a bedroom and bathroom, office which has been granted.
How ever we want to rent the main house out for occasional holiday let, airbnb,so when some one stays in the main house we can let them use the whole house, NOT the annex,as we will use that when customers stay.We will still use the main house when no holiday lets staying , so can anyone tell me if my neighbours from hell can stop us.
We then had our son and his wife staying for several months and a council tax was slammed on a so called annexe! This was because our American daughter in law stated she was in an apartment in her in laws house. Totally incorrect but the damage was done, she used it in a visa application and someone came to investigate No one in the council has been easy to deal with or the appeal
There is only one entrance into the house and so called annexe and no exit
No one lives in the annexe it is just part of our house
Never built or adapted as a annexe
If we take the kitchenette out will we stop the annex council tax
Estate agents/ friends were shocked but we did lose an appeal several years back The so called annexe used to be a hobbies room for the last owners.
Why are we penalised having a bathroom downstairs and a kitchenette
This is used because we have an Aga in main kitchen and it is turned off in summer so we use a free standing cooker in the kitchenette which we have done for years
The council class us as having a flat, we could not even sell the property only as one property
Impossible to let out as tenants would be coming into our main house all the time
Are we totally at a loss cause
My mother sadly went into care with dementia and we started to rent the annexe out under the rent a room scheme to pay for care fees. We thought this was OK (although we have now learnt we can't as the buildings are not connected).
While we had a friend living there under the rent a room scheme we had a visit from the council tax assessor who rebanded it as Band A and our friend has now paid the council tax for four years.
I am now told that if the council is charging us council tax for all this time then we could apply to have a change of use for the annexe and rent it formally as a separate residence. Is this correct? I find the whole planning vs council tax departments very confusing - particularly when they are all part of the same council! Any advice hugely appreciated
Do we have to inform any department.
1. Would we have to pay 2 lots of council tax on this? Or would it be classed as one property after we finish the work?
2. Do we need to get permission from the council to do this?
The annex was built in 2003 and as far as I can tell from the council website the property is registered under Band A.
Thanks!
We have an annexe which was built when the house was built. There is a door from our main house (internal door) which leeds into the annexe, there is also an external door for entry to the annexe. We have not rented out the annexe for many years. Council Tax has now gone up and no relief is available on council tax for the annexe any more, it has stopped this year. Our total is now £2976 for council tax for the year for both. As the annexe is no longer rented out we want to take the very old kitchen out and change the room to a bathroom. Also take the shower room out and join it up with the bedroom that is in the annexe. We spoke this morning to the council and they say we cannot have running water in there, or at least as far as this person knew. Someone more knowledgable in this matter will contact us in 48hrs. What do you know about incorporating the annexe into the main house.
My husband and I bought a 3 bedroom house which already had and annex extension built above the garage attached to the house. The annex can be accessed internally as well as externally with stairs which lead to an door which opens outside on the side of the house. We have lived in the "main house" and rented the annex to a lodger. We are now renting the "main house " to a family as well as renting the annex to a separate individual. The council are now saying we need planning permission or consent to do this even through the property was already built in this way when we bought it. Please advise how if possible we can evidence that this is still a single dwelling house or that we have not changed the use of the property or obtain retrospective permission.
Many thanks
Lizzy
The stables we wish to convert into a self contained granny annex was built by me and I used a concrete base (slab) with steel mesh reinforcement. It's quite substantial and have not seen any movement in 12 years.
My question is, when we are converting these stables I understand Building control will monitor it to some extent. My question is, would they be happy enough with the concrete base already in place.?
Many Thanks
We have some stables that are now redundant because the Council are going to build on the fields we rent to graze the horses. We are considering what to do with these stables and assume we will not need planning to turn it into something useful, such as a granny annex. However the stables are around 500 feet away from main house so for practical reasons would want to extend our drive down to new granny annex,
My question is, will we have an automatic right to turn the stables into residential building (still tied to house) and is there any planning restrictions on extending our drive down the garden?
The stables are about 6 x 8 metres
Could my wife and I live in it and rent the house?
Grateful for any advice.
Will the council allow us to let it out at all, when they have originally given permission for a family member?
Many thanks if anyone can clarify this for me.
We own a house with an attached annexe (previously our garage).
The annexe was separated on the land registry by the previous owner and purchased
by somebody else who lived in there.
The water stop tap in our house stops the water in the annexe as well as ours.
Likewise.... if the annexe turns off its electric mains - Our electric is cut off.
The person who lived in the annexe passed away unfortunately and the annexe
Was repossessed with solicitors instructed to sell it.
I spoke to the Local council planning department because we were considering
whether to make an offer or not. They told us that as far as they were concerned
the annexe is still part of our building and wasn't given planning permission
to be anything other than our annexe for our own private use.
I have asked the selling estate agent / selling solicitor to investigate further.
As stated earlier - it is separated on the land registry - but no planning
Permission to separate completely has come to light yet.
So........
Would that mean that they can only sell back to ourselves??
Because its can only be used by ourselves without PP to separate.
The estate agent was very keen for us to make an offer. They have not
put the annexe on the market or put any for sale signs up. Which I thought was
a bit strange. They said if we made an offer they would give us first
refusal and chance to purchase before it went on the open market.
Again.... I thought that was a bit strange......
So here's my conspiracy theory :
They already know they have no choice other than to sell
back to ourselves - but they are trying to hide this fact - because that
Puts us in a very strong position obviously.
Would welcome your thoughts
Is it worth disputing this?
I have struggled to find a definition of an Annex, the council do not accept that the Valuation Office guidance in their publication Council Tax, Council Tax Bands and Annexes is relevant.
Are you able to give me a definition of an Annex that I can use to persuade the Council that my basement is indeed an Annex?
We have a house with an extension converted from a garage to a separate lounge and a kitchen at the back done by the previous owner. The extension has a separate entrance from inside the porch. Now the Valuation officer is coming to inspect to check its in the correct CT band. Would the Valuation Office Agency rate this extension as "self-contained" when there is no shower/bathroom? Would they consider it possible to be "let" separately?
> Has the council assessed the annex as being liable for separate council tax?
Yes. It was assessed for CT separately by Council at the time that the conversion was completed. But we believe that we should have appealed this at the time.
> Is there a discount for unoccupation or family in the main house using it as part of the main living accommodation?
After the tenant vacated around May 2017 the Council gave a 1 month discount as unoccupied.
We could argue that it is now being used as overflow living accommodation and storage by our family.
Thanks your quick reply. MR
• It is an integral part of the main house. It is a converted roof space above integral garage & other outbuildings accessed internally from the main house. It has its own stairway leading to its own front door.
• All its utilities are accessed via the services provided and paid for by the main house; including water, sewerage, electricity and heating oil.
• Access to its front door from the road is only possible over ground and security controls exercised from the main house.
The conversion was completed in late 2007, and was immediately let to a ‘housekeeper’ of the main house. The architect did not discuss with us whether its assessment to CT was in any way subject to interpretation or negotiation with the Council.
The annexe has been vacant since June this year, after offering the whole property for sale, as yet unsuccessfully. Changes in the recent Budget (and uncertain prospects for a quick sale!) mean we should try & get the Council to agree to drop the assessment.
Please could you advise what criteria Councils use to determine whether CT is assessable on such annexes, whether there may be other matters I may have missed which may help our case.
Many thanks, MR
If i decide i no longer wish to rent, will i still be liable for the council tax if it remains empty ? Alternatively i would like to make available for my children (Aged 12 & 13) to use a s "Snug" / Homework / Chill out room ? Will i be liable for council tax if it is for our own sole familly use ?
I was hoping you might be able to assist with a few queries I have.
I moved out of my parents’ house because I had a child (she is now 6 months) and got married. I am currently renting. However, I no longer wish to rent and don’t want to/can’t afford to buy a house.
My idea was to move back to my parents but to get a log cabin the back garden. There are only 2 neighbours it might possibly affect, but I don’t think I will have any trouble with them.
1. Do you think I am likely to be able to prove it is permitted development if it has no cooking facilities (just a kettle and fridge for my brews) and I have to use the main house to cook? I would like the cabin to have a toilet, bath and we will obviously be sleeping there. I will also be able to prove that I still have a bedroom inside the main property with my stuff in it.
2. If the VOA deem that it needs to be banded for C Tax purposes; does this stick with you for life? If I was to turn it into a summer house eventually (a few years down the line) with no bedroom or maybe take the bath out could I get them out to look at it again? I am really conscious of my parents having a house with 2 council tax bands and how difficult that might be to sell it later down the line.
This is likely to be a semi-permanent thing. I will be living there for the next four years and saving and then we are likely to use it as a base whilst we do some travelling with our daughter.
Any advice would be much appreciated. I was originally looking at extending my parents property but it is very costly and I can get a properly insulated log cabin for about £10k that will do the job which we can turn into a mini house.
Many thanks and take care, rob
the 3 bed house we bought had the adjoining garage converted to a self contained annex about 30 years ago. Upstairs is a 3 x 8 m room with kitchenette, downstairs same with shower room in an additional space 1.5 x 3 m.
The annex is accessible through a normal doorway from our dining room, but also has its own exterior access.
No planning permission was obtained and no records with the council exist.
As it is so long converted is there any risk going now to the council and asking them to certify it?
At present we use the annex as additional living space for our family, but clearly it is designed for inter-generational living or perhaps a lodger or au pair.
As the council basically don't know about it we're only paying council tax on the main house, but I don't really see why more should be paid anyway given its current usage.
I would like to try to get the house 'right' with the council as clearly it will impact the resale potential eventually as not everyone will take a chance as I have that no issues will arise. I wish I could get independent advice from an ex-council planner as to what might go wrong with 'coming clean' about the house as it is.
enforceable". You may have a case especially if you feel that the section 106 is unreasonable (it's only one dwelling and you own the access road so the infrastructure implications are tiny).
We don't want to move, but when it's no longer required for my parents what do we do with it? We don't particularly want to be landlords. We'd like to sell it but how easy is it to get the section 106 removed.
I have a converted garage at the end of the garden that was granted conversion for a granny annex. My mother in law was in there during her cancer treatment. After she passed away I let a friend of mine stay in there and he is still there. There is no rent being charged as he was homeless.
The council is now saying that this is now not as the planning consent.
Can you help advise what I have done wrong?
Thanks
Mark
Does being a relative in any way disqualify me from being a Landlord to my mother in annexe accommodation?
Scepticus 58
The Council have now applied a 25% increase to the council tax for second homes in the area and have included our annex, because they have now considered this a second home, although all the services to the main house are shared with the annex.
We are happy to pay both council taxes on the main house and the annex, but certainly cannot understand the Council thinking on charging the second home premium of 25% on the annex. Is this action correct? and what if we sell the house?
I have recently moved to house which has a converted outbuilding. We are looking to make this self contained for use as a holiday let. Would this be liable for additional council tax if it is not let out all the time?
thanks in advance.
WL
Yet another point, when first installed, the annex attracted only 50% council tax when empty and since the rest of the house had had a banding reduction due to the reduction in size, the total council tax was not alot more than as a single property. Now the charge is 100% and could be more.
The point, I want to make is that when I asked, "Trading Standards" a few years ago (considering living abroad for a while), they said that I could not describe the rest of the house as self contained if I wanted to let it. However, the local authority take the contrary view.
A question is, what will HMRC consider it to be when selling for the purposes of capital gains tax?
Thanks!
I'm in the midst of converting part of my property to create a separate living space for my 85 year old mother. The plans State 'the annex is to be occupied only in conjunction to the original property, and shall not be let, sold, or used as a separate living space'.
The space consists of a lounge, kitchen, bedroom and bathroom. It has its own entrance, but there is an internal doorway connecting the annex kitchen, to the main house kitchen.
My question is whether we can charge my Mum rent under the rent a room scheme? Also, she currently gets help with her rent from the local council, would she be able to continue to get this help? Would these arrangements cause the council to reassess the type of use?
Many thanks
If you split a house or bungalow in to two separate dwellings do you have to separate the utilities for legal or mortgage purposes as I have been told that until they are separated it would not be a freehold property and so will be unmortgagable.
Many thanks - all advice will be appreciated!.
Are there anyways around this rule as it seems silly ripping the kitchen out and a longer walking up our garden to share ours...
Looking for a bit of advice - I'm interested in buying a semi detached house which has a self contained flat in the basement that the owner created for their eldest. I've since discovered this attracts its own council tax fee, as a flat. I have no interest in having a flat and want to use it as a kids play room. It has a kitchenette, shower and lounge (currently with a bed) and the access is from a door opening in to the garden.
Can anybody advise me on what I would need to do in order to return it to a room in the house, as far as the council tax is concerned? I would like to keep the shower if possible.
Thank you!
I am looking at converting part of my house into an annex for my a relative (over 65)
The annex utilities (oil heating, electric, water) will remain as one with the main house.
The annex itself will have its own external access and will not have any internal access to the main house and will consist of:
1 x Kitchen
1 x Living area
1 x Staircase
1 x Bedroom
1 x Bathroom
I am wondering if planning is required as there will not be any extension, the property is in South Wales not sure if this impacts the planning implications.
Thanks
Before moving we obtained permission from the council to not run a holiday lets business, and instead use the building as storage, a gym, and for visiting guests.
We have now been approached by the council to pay secondary, and tertiary council taxes for the previous holiday lets.
Given that planning permission prevents continued occupancy, can they do this?
Many thanks,
Jon
where do we stand with council tax and planning permission?
This might be a tricky one.
I rent a room in a house as a lodger. No problems there. The owner has said I can build some dog kennels and rescue dogs and rehome them. I would be a registered charity. Next to the kennels there is a garage building. I would like to turn this into an area for potential foster owners to come and stay for a night with a dog before it was placed in its new home. It would be rent free, and very rarely occupied. There wouldn't be a separate kitchen, but the area would incorporate a small place to prepare food and drink, and there is a toilet there already.
What should I do?
Thanks in advance
I converted garage inin to a 2 story attached to the main house. It was built with planning permission as an extension. I have now built a small kitchen, put a small staircase to go to the room and closed 2 enter emcee from the main house. There is a separate access to it from the back.
Do I need council permission to rent it and also do I need to pay council tax?
Thanks for the reply in advanced.
As the tenants could we be in trouble for this?
Have taken a few measurements and will try to find someone to help as am pretty sure I will need planning permission
Good article. I'm buying a house with an annex to the side of the house, but set towards the back. I want to extend the footprint either up or at ground level and I was wondering that assuming there were no visual impacts with neighbours (as it is secluded etc), could the council object, considering it is already inhabited under an existing 1990's planning consent?
If we believe that there is no chance of getting this through we don't want to risk buying the property.
Regards
Tom
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