What Is a Granny Annexe? The Complete 2026 Guide for Families

A three-minute film on what makes an annexe self-contained, the three kinds, and what to agree as a family before anyone moves in.

The short answer

A granny annexe is a self-contained home for a relativeAttached to the house, converted from existing rooms, or a separate building in the garden. To count as self-contained it needs its own kitchen, bathroom and entrance.
It sits between staying at home and moving into a care homeA parent keeps their own front door and routine, and family is close enough to notice if something changes.
Planning permission and council tax both usually applyA self-contained annexe almost always needs planning permission before it is built, and its own council tax band once it exists, though a dependent relative living there can remove the bill entirely.
Building one is a five or six-figure decisionA standard one-bedroom annexe costs £70,000 to £115,000 to build, so it is worth weighing against buying a house that already has one, or paying for care in the home your parent already has.

This page is the overview. The guides listed under find, build, money and care go into each part in full.

Free to download

The granny annexe decision planner, to fill in as a family

The questions in this guide as pages to work through with your parent and any siblings before anyone builds or buys: what to ask your parent first, the self-contained test, build, buy or convert, what each route does to their house and savings, and what to agree before moving day.

Questions for your parent and siblings, with space for their answers
The three routes side by side, with 2026 build costs and care rates
A family agreement on visits, bills, shopping and repairs

What it is

What is a granny annexe? The definition and the three types

A granny annexe is a self-contained home for a relative, with its own kitchen, bathroom and entrance, attached to a family home, converted within it, or built separately in the garden. Both spellings, annexe and annex, are in everyday use. Neither is a legal term, which is why the self-contained test below matters more than the name.

The three types of granny annexe

Attached annexe

A portion of the main house sectioned off, usually on the ground floor, with its own kitchen and bathroom built in.

Entrance:: Its own front door, or the main entrance shared
Planning:: Almost always needed once it has its own kitchen and bathroom
Best for:: A parent who wants to be under the same roof but living independently

Granny flat (a converted floor or rooms)

An existing floor, wing or set of rooms turned into a self-contained flat within the building, common where a house is already split over floors.

Entrance:: Its own front door built into the existing structure
Planning:: Not needed while it stays non-self-contained, needed once it has its own kitchen and bathroom
Best for:: A larger or multi-floor house with little or no garden to build in

Detached ancillary building

A separate structure in the garden, built new or converted from an outbuilding, connected to the house's utilities rather than standing alone.

Entrance:: Fully separate, with its own front door
Planning:: Almost always needed, though a caravan-style annexe kept for family use can sometimes avoid it
Best for:: A parent who wants full privacy and separation, where there is enough garden to build in

The dark block in each diagram is the annexe. The pale block is the rest of the house.

A cutaway of a one-storey garden annexe with its own front door and coat hooks, a shower room, a kitchen with a small table and an armchair, and a bedroom — Its own front door, shower room, kitchen and bedroom are what make an annexe self-contained, rather than a large bedroom in the main house.

What makes any of the three an annexe, rather than a large bedroom, is being self-contained: somewhere to sleep, somewhere to cook, and somewhere to wash, that the rest of the household does not need to use. That single test decides most of what follows in this guide, including whether planning permission is needed to build it and whether it gets its own council tax bill once it exists.

An annexe is one of several ways to keep a parent close without a care home. The housing options for an older parent and community retirement living are two of the others, and the full comparison of care at home against a care home sets out the whole picture, including what changes if your parent needs nursing care rather than help with everyday life.

Find, build or pay for one

Every granny annexe guide, by what you need to do next

The guides are grouped by where you are starting from: looking for a house that already has one, building one, working out the money and who owns what, or planning care for a parent who will live there. Each guide below covers one of those in full, so this page can stay an overview.

If you are not sure where to start, the questions in build, buy, or convert below point towards the right route, and the decision planner further down puts them on paper to fill in with your parent and any siblings.

Why families consider it

What a granny annexe can offer that staying put or a care home cannot

An annexe is a compromise between two harder choices: a parent alone in a house that is getting difficult for them, or a parent in a care home they did not choose. It is worth being clear about what it solves, and what it does not.

Easier to spend time together

Visiting or having a parent round for dinner stops depending on a car journey. Family can look in on the way to work, or hear if something is wrong, without planning a trip.

More independence than a care home

A parent keeps their own front door, their own kitchen, and visitors whenever they like. Family involvement grows without anyone else deciding when they eat or who they see.

Care can be added without another move

Hourly visits, then more visits, then live-in care if it comes to that, can all happen in the same annexe. Moving between homes as needs change is unsettling, and an annexe avoids at least one of those moves.

The proceeds of a parent's own house can fund it

Where a parent is selling their existing home to move, the proceeds can go towards the annexe, towards care, or towards both.

None of this makes an annexe the right answer for every family. It works best when a parent wants to remain independent and is well enough that living semi-separately is realistic, and when the family has the garden, the rooms, or the budget to create one. Where nursing needs are frequent, or a parent would be lonely without company through the day, a care home or community retirement living can suit them better than living alone a few steps from the back door.

What tends to go wrong

What tends to go wrong, and how to head it off

An annexe changes a family's day-to-day life as much as it changes a parent's. The problems below are foreseeable, and worth talking through before anyone builds or buys anything.

Worth agreeing before you start

Set times you expect to see each other, so neither side feels watched or ignored
Agree in writing how bills, food shopping or repairs are split before the annexe is occupied
Talk to every sibling about who is doing the caring and what that is worth, before resentment builds
Ask your parent directly whether they would rather try a retirement village or stay where they are
Revisit the arrangement after six months, since what works on paper does not always work in practice

What tends to cause trouble

Assuming a parent will feel more independent than they would in a care home; for some people it feels like less
Leaving money between the generations undiscussed until a bill or an inheritance forces the conversation
One sibling taking on the daily caring without agreeing what that means for time, money or a future inheritance
Building or buying before finding out whether your parent wants to move at all

A daughter walks along the path from the family house to her parent's garden annexe with a mug of tea, past shopping left at the annexe door, a ladder against its gutter and its own electricity meter — Visits, bills, shopping and repairs are the everyday things worth agreeing before anyone moves in, and the decision planner has a page for writing that agreement down.

An annexe puts a family in closer contact than most are used to, and that can be the whole point or the whole problem depending on the relationship. It is not a failure to decide, after talking it through, that a care home or community retirement living suits your parent better. The difference between a nursing home and a care home is worth reading before ruling either out.

The money question

How the three main routes affect your parent's money

Families choosing between staying at home with care, a care home, and a granny annexe are choosing between three different things that happen to a parent's house and savings. Here is what each route does to both.

	What happens to the house	Typical weekly cost	What it does to savings
Stay at home with care	Kept, and disregarded in the means test while your parent lives in it	£1,050 to £1,400 live-in, or £18 to £25 an hour for visits	Pays from income and savings until they near the £23,250 upper capital limit, after which the council may help fund care at home
Move into a care home	Usually sold, and counted in the means test unless a partner, or a relative aged 60 or over or incapacitated, still lives there	£1,100 to £1,600, typically around £1,160	House proceeds and savings pay the fee until they fall to the upper capital limit, then the council contributes
Build or buy a granny annexe	A parent's own house is usually sold to fund the £70,000 to £115,000 annexe or the extra cost of a house that has one; the family home gains an asset rather than losing one	Building or buying is a one-off cost, then care on top: £18 to £25 an hour for visits, or live-in care if needed	What is left over from the house sale after the annexe stays as savings, rather than being spent on fees

Stay at home with care

What happens to the house: Kept, and disregarded in the means test while your parent lives in it
Typical weekly cost: £1,050 to £1,400 live-in, or £18 to £25 an hour for visits
What it does to savings: Pays from income and savings until they near the £23,250 upper capital limit, after which the council may help fund care at home

Move into a care home

What happens to the house: Usually sold, and counted in the means test unless a partner, or a relative aged 60 or over or incapacitated, still lives there
Typical weekly cost: £1,100 to £1,600, typically around £1,160
What it does to savings: House proceeds and savings pay the fee until they fall to the upper capital limit, then the council contributes

Build or buy a granny annexe

What happens to the house: A parent's own house is usually sold to fund the £70,000 to £115,000 annexe or the extra cost of a house that has one; the family home gains an asset rather than losing one
Typical weekly cost: Building or buying is a one-off cost, then care on top: £18 to £25 an hour for visits, or live-in care if needed
What it does to savings: What is left over from the house sale after the annexe stays as savings, rather than being spent on fees

Figures are PrimeCarers pricing data and typical UK care home fees for 2026, and the England capital limits for the care means test (£23,250 upper, £14,250 lower), unchanged since 2010. They are not a forecast for any specific family.

The annexe route is the only one of the three that turns a parent's house into an asset the family keeps rather than money spent on fees, which is why it appeals to families who can manage the upfront cost. It is not automatically cheaper: building or buying still costs tens of thousands of pounds before any ongoing care is added on top. Local authority funding explains how the means test works and when the council starts to contribute.

When a parent puts money into a family home, or the family buys a new house together, the question of who owns what comes up straight away. Buying a house with an elderly parent covers joint ownership, a declaration of trust and what happens to the house if care fees come later.

Build, buy, or convert

Deciding whether to build, buy a house with one, or convert what you have

There are three practical routes to an annexe, and the right one depends on your garden, your timeline and your budget more than on which sounds best.

A cutaway of a two-storey house where the ground floor at one end has become an annexe with its own front door, kitchen, bedroom and shower room, beside the family's own hallway and stairs — Converting rooms you already have is usually the cheapest route, and the annexe still needs its own kitchen, bathroom and front door to count as self-contained.

Questions that point towards the right route

0 of 5 ticked

Your house and garden

Do you have space to build in the garden?Little or no garden usually points towards converting existing rooms or a loft rather than a new detached building.
Could an existing garage or outbuilding be converted?Converting is the cheapest route by a wide margin, though it will often share a kitchen or bathroom with the main house rather than being fully self-contained.
Are you likely to move house in the next few years?A kit-built or mobile-home style annexe can sometimes be taken with you; a brick-and-block extension cannot.

Time and money

How soon does your parent need somewhere to move to?A build, from planning application to moving day, usually takes four to nine months. Buying a house that already has one can be faster if the right property comes up.
What is your budget, and where is it coming from?Savings, a parent's own house sale, a mortgage advance, equity release or help from family are the routes most people use to pay for a build or a purchase.

If nothing in your garden or your house works, buying a house that already has a self-contained annexe skips the build and the wait, though self-contained ones are not common on the market and searching for one takes a specific approach. How to find a house with a granny annexe for sale covers how to search Rightmove for one, since there is no tick-box filter for it. If building suits you better, how much it would cost to build a granny annexe breaks the cost down by size and by construction type, including the extra costs, VAT and timescales that sit around the headline build price.

You can get the free printable PDF to keep with this guide.

Permission, tax and value

Planning permission, council tax and what an annexe adds to the house

Whether an annexe is self-contained decides both planning and council tax, which is why the same design choices keep coming up throughout this guide. What it adds to the house, and what happens if it is let out later, follow on from the same test.

	The question	The short answer
Do you need planning permission?	Before you build	Almost always, once the annexe has its own kitchen, bathroom and front door. A householder application in England costs £548 from April 2026, and the council normally has 8 weeks to decide it.
Will it be charged council tax?	Once it exists	Yes, once it is self-contained, it gets its own band. A relative living there halves the bill, and a dependent parent, 65 or over or disabled, removes it entirely.

Do you need planning permission?

The question: Before you build
The short answer: Almost always, once the annexe has its own kitchen, bathroom and front door. A householder application in England costs £548 from April 2026, and the council normally has 8 weeks to decide it.

Will it be charged council tax?

The question: Once it exists
The short answer: Yes, once it is self-contained, it gets its own band. A relative living there halves the bill, and a dependent parent, 65 or over or disabled, removes it entirely.

Both tests turn on the same detail: whether the annexe has its own kitchen, bathroom and somewhere to sleep, separate from the main house.

Neither of these happens automatically, and neither is optional once an annexe meets the self-contained test. Do you need planning permission for a granny annexe sets out what each type of annexe needs, the fee and timescale in full, and what to do if an application is refused. Is a granny annexe subject to council tax covers how a band gets assigned, the discounts and exemptions in full, and what happens while an annexe stands empty.

It can add to what the house is worth

A well-finished, self-contained annexe can raise a property's value, though a cramped layout or one that swallows the whole garden adds far less. The value guide sets out the estimates and what moves them.

Letting it out separately is ordinary rental income

HMRC's Rent a Room Scheme covers furnished accommodation in your own home, not part of a building used as a separate residence. A fully self-contained annexe let on its own is likely to fall outside it, and is then taxed and governed by tenancy law like any other let. A planning condition may stop it being let at all.

An empty annexe is not automatically exempt from council tax

Only if a planning condition stops it being let separately. Without that, some councils charge more for a long-term empty home rather than less.

Care in the annexe

How care works once your parent lives in the annexe

An annexe changes where care happens, not whether it is needed. Family a few steps away can do a great deal, but help with washing, dressing, medication or nights is easier to plan before the move than after a fall or a hospital stay.

Care in an annexe is booked the same way as care in any other home. Carers on PrimeCarers are self-employed, and you choose and book them directly; PrimeCarers is an introductory service and does not provide or manage the care itself. Every carer has had their ID and right to work checked, holds an enhanced DBS check (or PVG in Scotland, Access NI in Northern Ireland) issued within the last 2 years, and has passed an online interview. Qualifications, training and references are not checked by PrimeCarers: references and reviews appear on each profile unverified, so ask the carer directly about their experience and training.

Live-in care, with a carer living in or next to the annexe

A live-in carer stays with your parent through the week and needs a bedroom of their own and proper breaks. On PrimeCarers, live-in care costs £1,050 to £1,400 a week with our fee included.

Hourly visits, for a morning and evening call

Where your parent only needs help at set times, a carer can visit for an hour or more, at £18 to £25 an hour with our fee included, while family cover the rest of the day.

Care in a granny annexe goes through who does what when family live a few metres away, when visits are enough, and when nights or a live-in carer make sense. Whether a live-in carer can live in the annexe covers the two set-ups families use: the carer sharing the annexe with your parent, or the annexe as the carer's own space next to your parent's home.

How to start

From this page to a decision

An annexe touches money, the family and the law all at once, so it is worth taking the steps in an order that avoids committing to a design before the bigger questions are settled.

1
Talk to your parent, and to any siblings, before anything else
First
Whether they want to move this close at all, and how caring responsibilities and money will be shared, matter more than any design decision that follows.
2
Ask the council for a care needs assessment
Free
It sets out what help your parent needs, which affects how big an annexe needs to be and whether a second bedroom for a live-in carer is worth building in.
3
Decide whether to build, buy, or convert
This month
Your garden, your timeline and your budget decide this more than preference does. Get quotes or start searching once you know which route fits.
4
Book care in the current home while the annexe takes shape
Ongoing
A build or a house search can take months. Hourly visits can start in the home your parent has now, and live-in care can follow in the annexe once it is ready.

Questions

Questions families ask about granny annexes

A self-contained home for a relative, with its own kitchen, bathroom, entrance and somewhere to sleep, also spelt granny annex. It can be attached to the main house, converted from existing rooms, or a separate building in the garden. A large bedroom with an ensuite is not an annexe unless it also has its own kitchen and its own entrance.

In most cases, yes, once it is self-contained. Do you need planning permission for a granny annexe covers what each type needs, the fee and how long a decision takes.

Yes, once it is finished and self-contained, though the bill depends on who lives there: a 50% discount for most relatives, and a full exemption for a dependent parent aged 65 or over or with a disability. Is a granny annexe subject to council tax covers the discounts and exemptions in full.

A standard self-contained one-bedroom annexe costs £70,000 to £115,000 to build in 2026, with professional fees, planning costs and utility connections usually on top. How much would it cost to build a granny annexe breaks this down by size and construction type.

It can, if it is self-contained and well finished, though a poor build or one that takes up most of the garden adds much less. Do granny annexes add value sets out the estimates and what changes them.

Some come onto the market, though they are not common. How to find a house with a granny annexe for sale covers how to search Rightmove for one, since there is no dedicated filter for it.

Not necessarily, at least not upfront. Building or buying an annexe costs tens of thousands of pounds before any ongoing care is added, while a care home or live-in care has no upfront cost at all. What an annexe offers instead is an asset the family keeps: a well-built, self-contained annexe can add to what the house is worth, in a way that weekly care fees never do. Do granny annexes add value works through what that can mean in pounds for a given house price. Care at home or a care home compares the ongoing costs of each route.

Then it is not the right answer, whatever the financial or practical case for it looks like on paper. An annexe works best when a parent wants the arrangement, not when it solves a problem for the rest of the family alone. Housing options for an older parent and community retirement living cover two other ways to keep them safe and independent without this particular change.

Yes, if it is not needed for a relative, but a fully self-contained annexe let on its own is unlikely to qualify for HMRC's Rent a Room Scheme, which does not cover part of a building used as a separate residence. It is then ordinary rental income, taxed and governed by tenancy law like any other let property. The scheme's £7,500 tax-free allowance (£3,750 each for joint owners) applies to furnished accommodation in your own home, such as a lodger's room. Check the current position with an accountant before you commit to either route, and check the planning permission for any condition that stops a separate let.

Hourly visits, then more visits, then live-in care can all be booked in the same annexe without a second move, as long as there is room for a carer and the layout suits your parent's needs. Care in a granny annexe covers each stage, and how many visits a week does my parent need helps you judge when visits stop being enough.

The complete guide to granny annexes