Mortgage for House with an Annexe
Mortgages for properties with granny annexes, dependent-relative annexes and income-producing annexes. From £250,000+.
Mortgages on houses with an annexe in 2026
A house with an annexe is a single freehold property with a self-contained secondary living space attached to or set within the grounds of the main dwelling. The annexe usually has its own bedroom, bathroom and kitchen, but it remains part of the main residence. It is not a separate dwelling. That distinction matters to the lender, to the planning authority, and to the SDLT position.
Fox Davidson arranges mortgages on annexed property from £250,000+ across England, Scotland and Wales. We work with full market access across the residential lender market: high street clearing banks, building societies with manual underwriting strength on country property, specialist residential lenders for income-producing annexes, and private banks for HNW the FCA high net worth rules buyers of £1m+ country houses with sizeable annexes.
What we have found over the years is that three things matter on an annexe property application that do not matter on a standard residential purchase. The annexe size relative to the main house (most lenders prefer under 40-50% of total floor area). The intended use (family, dependent relative, or income-producing). And the planning position (planning permission, Lawful Development Certificate, or restrictive Article 4 area). The right lender depends on which of those sits where.
Expert mortgage advice for annexed properties
A property with an annexe presents specific questions for mortgage lenders: is the annexe subordinate to the main house, will it be used by family or let separately, and does its size or facilities affect the property's classification? Most lenders are comfortable with annexes clearly subordinate to the main dwelling at under 40-50% of total floor area. Where the annexe approaches or exceeds the main property in size, specialist lenders or commercial terms may be required.
Multi-Generational Living
Annexes for elderly parents or grown-up children are treated sympathetically by most lenders where the annexe is clearly subordinate to the main house.
Annexe Rental Income
A small pool of lenders includes projected annexe rental income in the affordability assessment for purchase mortgages. More will use it on a remortgage where rental history is established.
Size Thresholds
Annexes under 40-50% of total floor area are generally accepted by mainstream lenders. Larger annexes typically need specialist lenders or a manual underwriting approach.
Planning and Building Control
We advise on whether planning permission, a Lawful Development Certificate, or building control sign-off is needed for your annexe, and how the planning position affects lender criteria.
Funding to Build an Annexe
Remortgage, further advance, second charge loan and bridging finance routes for raising capital to build an annexe on an existing main residence.
Granny Annexe Mortgages
Specific expertise in granny annexe mortgages, including cases where elderly parent funding from a property sale is used as the deposit on the new family home with annexe.
Annexe vs separate dwelling - the lender's test
The most important question on every annexe mortgage application is whether the lender treats the annexe as PART OF the main residence, or as a SEPARATE DWELLING. The answer determines the product, the rate, the LTV and the SDLT position.
- Annexe as part of the main residence. The lender treats the whole property (main house plus annexe) as a single residential dwelling, mortgages it on a standard residential product, applies standard residential LTV bands, and accepts the typical residential SDLT calculation. This is the outcome we work toward on most cases. Annexes that are clearly subordinate (under 40-50% of total floor area, shared access from the main house, no separate council tax band, no separate utility metering) usually qualify.
- Annexe as a separate dwelling. Where the annexe has its own front door from the public highway, its own council tax band, separate utility meters, planning permission as a separate residential unit, and is comparable in size to the main house, some lenders will refuse the case outright and others will require a specialist or commercial product. This route is harder, slower and pricier.
- The criteria that decide it. Size relative to main house, internal access (door from the main house into the annexe), separate front door, separate council tax band, separate utility metering, planning permission classification, and whether the annexe could be let or sold off separately. Most lenders apply a checklist. We work through it on the first call.
In our experience the cases that catch borrowers out are the ones where the annexe was built or converted some years ago and the planning position was never fully tidied up. A lender's solicitor will pull the planning history, and a missing Lawful Development Certificate or unenforced enforcement letter from the council can stall the case. The conversation we have early is whether the planning position is clean before instruction.
Annexe property lenders and rates in 2026
The active lender list for annexed property in 2026 is smaller than the standard residential market but broader than most borrowers expect. The right lender depends on the annexe size, the intended use, the planning position, the borrower's income profile, and whether the case falls inside or outside HNW the FCA high net worth rules.
- High street accepting annexed property. Halifax (case by case, sympathetic to subordinate granny annexes), Nationwide (case by case, manual referral on larger annexes), Santander (with size and use restrictions). These will typically lend on a standard residential product where the annexe is clearly subordinate and family-occupied.
- Specialist residential lenders. Skipton Building Society, Saffron Building Society, Newbury Building Society, Hodge. These hold strong on country property and manual underwriting. They handle larger annexes, annexes with separate utilities, and dependent-relative cases that fall outside high street criteria.
- Building societies with country-property strength. Suffolk, Furness, Cumberland, Yorkshire, Coventry, Leeds. Useful on Cotswolds, Lakes, Yorkshire Dales and coastal cases where the property and the annexe both need manual valuation reads.
- Private banks for HNW the FCA high net worth rules buyers. Coutts, Weatherbys, Investec, Barclays Private Bank, Arbuthnot Latham, Hampden & Co. Whole-of-wealth assessment, higher LTV bands on £1m+ country houses, manual treatment of large annexes including income-producing ones.
Indicative 5-year fixed rates for annexe property mortgages in 2026:
- HNW private bank (the FCA high net worth rules, country residence with subordinate annexe, sub-60% LTV): from BoE base + 1.5% = 5.25%
- Prime high street with subordinate annexe (clean planning, 60-65% LTV): 4.85% to 5.50%
- Mainstream annexed property (65-75% LTV, standard income): 5.00% to 5.85%
- Specialist annexed property (larger annexe, income-producing, 75-80% LTV): 5.65% to 6.50%
- Building society manual underwrite (country property, manual valuation): 5.25% to 6.00%
Rates and lender criteria are subject to change. Figures correct at time of publication. Always speak to your broker for up-to-date rates and lending criteria on your specific case.
Planning, Article 4 and council tax on annexed property
The planning position is the second binding constraint on an annexe mortgage (after lender size threshold). Three planning checks decide whether the case proceeds smoothly or stalls at the conveyancing stage.
- Planning permission or Lawful Development Certificate. Annexes built or substantially altered after roughly 2015 generally need formal planning permission. Older annexes may have been built under permitted development rights and the position is established by a Lawful Development Certificate (LDC). The lender's solicitor will pull the planning history. A missing LDC on an older annexe is the most common stall point we see.
- Article 4 direction areas. In Article 4 areas (parts of London boroughs, conservation areas, AONBs, some National Park towns), local councils have removed permitted development rights and require full planning permission for annexe creation or change of use. If the annexe sits in an Article 4 area, confirm the planning position is fully consented before instructing the lender. Article 4 disputes are slow and expensive.
- Council tax banding. An annexe with its own council tax band is treated by some lenders as a sign of separate dwelling status. Where the council tax is a single band covering both main house and annexe, the lender is more comfortable treating the whole as one residence. A separate band does not automatically disqualify, but it raises the question and shifts the lender shortlist.
A pragmatic broker observation. We sometimes see borrowers buy a property assuming the annexe is fully consented, only for the lender's solicitor to find a missing LDC on a 1990s conversion. The fix is usually a retrospective LDC application, which adds 8 to 12 weeks to the case and several thousand pounds in fees and solicitor time. If the planning position looks suspicious, run it past your conveyancer BEFORE you offer.
SDLT on annexed property in 2026
The SDLT picture on annexed property has simplified since 1 June 2024. Until then, Multiple Dwellings Relief (MDR) allowed buyers of property with a self-contained annexe to claim a lower aggregate SDLT figure by treating the annexe as a separate dwelling. MDR was abolished by HMRC on 1 June 2024 for transactions completing on or after that date (purchasers who exchanged contracts on or before 6 March 2024 remained eligible under transitional provisions). The current position is straightforward.
- Standard residential SDLT applies to the full purchase price. Annexed property is treated as a single residential dwelling for SDLT purposes. SDLT is calculated on the full price using the residential bands, with no MDR adjustment available for the annexe.
- Additional dwelling surcharge if you already own another property. If you, or your married partner, already own a UK residential property at completion, the 5% additional dwelling surcharge (raised from 3% on 31 October 2024) applies on top of the standard SDLT, calculated on the full purchase price. The annexe does not generate a separate surcharge.
- First-time buyers. A first-time buyer purchasing an annexed property as their main residence qualifies for first-time buyer SDLT relief on the full purchase price under the standard residential rules, provided the property is under the FTB relief threshold and no co-buyer has owned property before.
In Scotland the equivalent transaction tax is LBTT with an 8% Additional Dwelling Supplement where relevant. In Wales it is LTT with a 5% higher-rate surcharge where relevant. Run the figure on your specific case before you offer.
Cotswolds couple, family home with granny annexe, £780,000 purchase
A representative case from earlier this year, anonymised. Married couple in their late forties. Husband 49, technology director, £130,000 base plus £40,000 bonus average. Wife 47, GP partner, £95,000 declared profit share. Combined gross £210,000. Two teenage children at home. Husband's 78-year-old mother to move into the annexe after the sale of her own home in Cheltenham.
Target purchase: £780,000 four-bed stone farmhouse near Chipping Norton with a converted single-storey annexe at the side of the main house. The annexe is approximately 38% of total floor area, internal access from the main house plus a side garden door, shared mains water and electricity, single council tax band covering the whole property. Planning permission for the annexe conversion was granted in 2018 and the LDC is on file.
Deposit £195,000 (25%, with £140,000 coming from the sale of the mother-in-law's house and £55,000 from the couple's savings). Borrowing £585,000 at 75% LTV on a 20-year capital-and-interest term.
SDLT calculation: standard residential SDLT on £780,000 in 2026 = £29,000. No MDR available (abolished June 2024). No additional dwelling surcharge because the couple's existing flat is being sold simultaneously and the new house is their main residence. Total SDLT £29,000.
Affordability: Halifax 5-year fixed at 5.15% on a standard residential product, treating the annexe as subordinate to the main house under their published criteria (annexe under 40% of floor area, internal access, single council tax band, dependent relative occupation). Monthly payment £3,920. Comfortably within the couple's combined income at a 4.5x multiple.
Sarah's note: this case worked cleanly at Halifax because the annexe is genuinely subordinate, the planning history is clean, and the elderly parent moving in fits Halifax's dependent-relative criteria. On a similar profile with a 45% annexe or an income-producing intention, we would have steered to a specialist lender on slightly higher rate and a more flexible read.
When an annexe mortgage works and when it does not
The cases we place. Annexes that are clearly subordinate to the main house (under 40-50% of floor area), with clean planning history (planning permission or LDC on file), internal access from the main house, single council tax band, and family or dependent-relative occupation. Mortgages at or below 75% LTV. Stable PAYE, self-employed or HNW income covering the combined affordability at the lender's stress rate.
The cases we steer away from at the high street and route into the specialist or private bank market instead. Annexes that approach or exceed the main house in size. Annexes with full independent access from the public road and separate council tax band. Income-producing annexes let on a long Assured Shorthold Tenancy (these stop being "annexes" in the lender's eyes and start looking like buy-to-let units). Annexes built without consent in Article 4 areas where the council has open enforcement files. Annexes with kitchen-and-bathroom layouts that suggest the property could be split into two separate units later.
One blunt point. If an estate agent has marketed the property as "ideal for Airbnb income from the annexe" or "perfect for an income-producing granny flat", the lender will read those listings before instruction. Marketing wording matters. We sometimes ask the estate agent to remove the income-producing language before the mortgage application is filed, so the lender's underwriter sees a straight residential family use case rather than a buy-to-let in disguise.
How Fox Davidson arranges your annexe property mortgage
The use of the annexe and its size relative to the main house are the two key factors in lender selection. We work the case in three steps to make sure the right lender is identified before instruction.
Step 1: Annexe Assessment
We establish the annexe size relative to the main house, current or intended use (family, dependent relative, let, or vacant), planning and building control position, council tax banding, internal access, and whether annexe income needs to support the affordability assessment. This is the early conversation that decides which lender shortlist to draw up.
Step 2: Lender Selection
We identify lenders whose policy explicitly permits annexed properties with your specific use case. Lender policies vary significantly on annexe rental income, size thresholds, and planning requirements. For HNW the FCA high net worth rules cases we add the private bank route in parallel.
Step 3: Application and Completion
We manage the full application, ensure planning documents are in the conveyancing pack from day one, and advise on any conditions the lender imposes regarding annexe use or documentation. We stay on the case through underwriting and valuation to formal mortgage offer and completion.
Speak to an annexe property mortgage specialist
If you are buying or remortgaging a property with an annexe from £250,000+, we will tell you which lenders match your annexe profile and what the SDLT picture looks like, before you offer.
Frequently Asked Questions
Can I get a mortgage on a house with a self-contained annexe?
Yes. Most mainstream lenders will consider properties with self-contained annexes provided the annexe is clearly subordinate to the main house. Fox Davidson identifies which lenders have favourable policies for annexed properties.
Can annexe rental income help my mortgage affordability?
A small pool of lenders includes projected annexe rental income in the affordability assessment at the purchase stage. More lenders will consider it on a remortgage where the rental history is established. Fox Davidson identifies these lenders specifically.
What if my annexe is for an elderly parent?
Annexes for family members are viewed sympathetically by most lenders. Many mortgage providers treat this favourably where the annexe is not being let commercially. The key requirements are that the annexe is subordinate to the main house and the solicitors confirm there are no unusual financial arrangements.
What size can an annexe be before it becomes a problem?
As a general guideline, lenders prefer annexes under 40-50% of total floor area. Where the annexe approaches or exceeds the main property in size, specialist lenders may be required. Fox Davidson advises on the size threshold implications for your specific property.
How do I fund building an annexe?
Options include remortgaging to release equity, a further advance from your current lender, a second charge loan, or bridging finance for larger projects. Fox Davidson advises on the most appropriate funding route for your circumstances.
Does the annexe need planning permission?
For annexes built after approximately 2015, planning permission and building control sign-off are generally required. Older annexes may have been built under permitted development rights. Fox Davidson advises on the planning position before applications are submitted.
What is an Article 4 direction and how does it affect an annexe?
An Article 4 direction is a local planning measure that removes permitted development rights in a defined area. In conservation areas, parts of London boroughs, AONBs and some National Park towns, councils use Article 4 to require full planning permission for annexe creation or change of use that would otherwise have been permitted development. If the property sits in an Article 4 area, confirm the annexe planning position is fully consented before instructing the lender. Article 4 disputes are slow and expensive, and a lender's solicitor will pull the planning history.
How does council tax banding affect an annexe mortgage?
An annexe with its own separate council tax band is treated by some lenders as a sign of separate dwelling status. Where the council tax is a single band covering the whole property (main house plus annexe), the lender is more comfortable treating the whole as one residential dwelling. A separate band does not automatically disqualify the case, but it shifts the lender shortlist. We work through the council tax position on the first call.
Can I claim Multiple Dwellings Relief on the SDLT for a house with an annexe?
No. Multiple Dwellings Relief (MDR) was abolished by HMRC on 1 June 2024 for SDLT transactions completing on or after that date. Purchasers who exchanged contracts on or before 6 March 2024 remained eligible under transitional provisions, but any new purchase of an annexed property in 2026 is treated for SDLT purposes as a single residential dwelling on the full purchase price. Run the SDLT figure on the Fox Davidson stamp duty calculator before you offer.
Can I let the annexe out as a buy-to-let?
Letting an annexe to a long-term tenant on an Assured Shorthold Tenancy changes the lender conversation significantly. Most standard residential lenders will not permit a let-out annexe under their residential criteria, because they treat it as a buy-to-let unit by use rather than by title. A small specialist lender pool will lend on a residential main house plus an income-producing annexe, with the income treated against ICR. Speak to us early if income letting is the intention. Short-term holiday letting of an annexe (Airbnb, Booking.com) is treated even more cautiously and usually requires a holiday let arrangement on the annexe specifically.
Do private banks lend on country houses with large annexes?
Yes. Private banks (Coutts, Weatherbys, Investec, Barclays Private Bank, Arbuthnot Latham, Hampden & Co) lend on £1m+ country residences with sizeable annexes for HNW the FCA high net worth rules clients (income above £300,000 or net assets above £3 million). Whole-of-wealth assessment lets them treat larger annexes flexibly, including cases where the annexe runs to 50% of total floor area or has a partially income-producing use. AUM expectations apply in proportion to the loan size.
Can I use a bridging loan to buy a country house with an annexe?
Yes, in specific situations. Regulated bridging finance is available for owner-occupiers who need to complete on a country house with an annexe before the existing main residence sells (a chain break), or where the planning position on the annexe needs to be tidied up before a term mortgage lender will instruct (the bridge gives time for a retrospective Lawful Development Certificate to land). We arrange the bridge alongside a term mortgage exit so the exit lender is identified before completion.
Why a specialist broker matters on annexed property
Most annexe property cases sit at the harder end of the residential lender's day. The annexe size, the planning position and the intended use all introduce policy questions that the high street's automated systems were not built to answer. The right lender is rarely the lender on the rate sheet at the top of the comparison table.
What we find with annexe cases is that the lender that wins is the one whose published criteria match the annexe profile exactly. Halifax will say yes to a subordinate granny annexe with internal access and a single council tax band. Skipton will say yes to a 45% annexe with separate utilities where the borrower is HNW. Saffron will say yes to a small income-producing annexe at 25% of total floor area. A high street system that just runs the case through automated affordability will frequently decline an annexe profile that a manual underwriter would have approved.
In our experience, around a third of annexe enquiries we handle had already been declined by at least one high street lender before the borrower came to us. The decline is usually a binary policy hit on the annexe (size, council tax, planning, or use), not on the borrower's affordability. Once we identify a lender whose policy explicitly accommodates the specific annexe profile, the case goes through.
The cases we find easiest to place are clean subordinate granny or dependent-relative annexes under 40% of floor area with planning fully consented. The cases we work hardest on are HNW country houses with larger annexes where the borrower wants flexibility on letting the annexe out occasionally, and country property cases where the planning history needs tidying up before instruction. We do both.
Indicative rates and lending metrics. Rates and lender criteria change frequently and vary by scheme type, location and borrower profile. Speak to us for figures specific to your case.